When you've got a tick function like this:
USTRUCT(BlueprintType)
struct FNameofGameStructTickFunction : public FNameofGameStructParentTickFunction {
    GENERATED_BODY()
public:
    GAMENAME_API FNameofGameStructTickFunction();
};

Add code like this to the bottom:
template<>
struct TStructOpsTypeTraits<FNameofGameStructTickFunction> : public TStructOpsTypeTraitsBase2<FNameofGameStructTickFunction>
{
    enum
    {
        WithCopy = false
    };
};

========================== First do: ==========================
Convert GameProjectGenerator to 4.27
Generate project using commandlet
Then open it in Rider/VS.

========================== Then do, in no particular order: ==========================
Find out what version of mod.io game currently uses. At time of writing it is https://github.com/modio/modio-ue4/releases/tag/v2.16.1792. Paste the 'Modio', 'ModioTests' and 'ThirdParty' folders from this into Plugins/Modio/Source, replacing the existing 'Modio' folder. Do not replace the .uplugin file.

Comment out/delete #include "ModioModID.h" in ModioSubmissionExtensionLibrary.h in that ModioEx game module. Then add '#include "Types/ModioCommonTypes.h"'.

Add 'config = Engine' to the 'UCLASS' macro in any error that says "UCLASS(defaultconfig) not defined"

"GetHashType" errors:
In Struct file FChunkID, add this line to the bottom of the file, outside of the struct: 
FORCEINLINE uint32 GetTypeHash(const FChunkId) { return 0; }

In Struct file FMusicHandle, add this line to the bottom of the file, outside of the struct: 
FORCEINLINE uint32 GetTypeHash(const FMusicHandle) { return 0; }

"Override of UFUNCTION in parent class ... cannot havae a UFUNCTION() declaration above it" errors:
Comment out or remove the function both in the .h file and the .cpp file (if it has a declaration)

Errors that look like this: "ActorFunctionLibrary.gen.cpp(153): [C2664] 'void UActorFunctionLibrary::DissolveMaterials(UObject *,const UMeshComponent *&,float)': cannot convert argument 2 from 'UMeshComponent *' to 'const UMeshComponent *&'":
Remove the const before the arguments that have the error (remember to also remove them in the definition stub too)

Packing for first time, "game target not found" errors:
Copy the EditorTarget file, rename it to FSDGame.Target, and inside of it change target type to Game

In "ShowroomStage.cpp" inside of the implementation of the constructor, comment out "this->SceneCapture = CreateDefaultSubobject<USceneCaptureComponent2D>(TEXT("SceneCapture"));" 

========================== No longer shows but may still be relevant to know: ==========================
Add "OnlineSubsystem" and "GameplayTasks" to "FSD\FSD.Build.cs" in the "PublicDependencyModuleNames" list - if already there, ignore

Packing for first time, linker errors:
Ctrl + T look for IMPLEMENT_MODULE (located in FSDModule.cpp). Replace this line with IMPLEMENT_PRIMARY_GAME_MODULE(FDefaultGameModuleImpl, FSD, "FSD");

Convert GameProjectGenerator to 4.27

Right click generated project and open with IDE (e.g. Rider)

Rename the following files in UWorksWeb to add a "2" at the end (or anything. Make sure refactor function is used to rename all instances of those files):
    - FindOrCreateLeaderboardDelegateDelegate.h
    - FindOrCreateLeaderboardMinimalDelegateDelegate.h
    - GetNumberOfCurrentPlayersDelegateDelegate.h
    - GetNumberOfCurrentPlayersMinimalDelegateDelegate.h

Replace UCLASS(DefaultConfig) with UCLASS(config = Engine, DefaultConfig) in:
    - GoogleAnalyticsSettings.h
    - LivPluginSettings.h
    - DLSSSetings.h
    - VRGlobalSettings.h (don't remove BlueprintType flag)

Replace UCLASS( ProjectUserConfig) with UCLASS(config = Engine, ProjectUserConfig) in:
    - DLSSOverrideSettings.h

Remove BlueprintReadWrite flag from:
    - LiveCaptureContext.h
        - TArray<TWeakObjectPtr<UPrimitiveComponent>> HiddenComponents;
        - TArray<TWeakObjectPtr<AActor>> HiddenActors;
    - UInt32.h - uint32 Value;
    - UInt64.h - uint64 Value;
    - DLSSSettings.h - uint32 NVIDIANGXApplicationId;
    - MeshComponentInfo.h - all properties
    - TexSource.h - all properties

Remove BlueprintCallable flag from:
    - LightReceiveInterface.h - all functions

Comment out UFUNCTION(BlueprintCallable) from following functions in ReceiveLightActor.h:
    - UseActorCustomLocation
    - GetActorCustomLocation

Set the "_MAX UMETA(Hidden)," to "_MAX = 0xFF UMETA(Hidden)," in:
    - EUGCMatchingUGCTypeBP.h
    - EItemPreviewTypeBP.h

In IpNetDriverUWorks.h and cpp files.
Add as a parameter to the constructor: "const FObjectInitializer& ObjectInitializer"
Add before the "{" in the cpp file: ": UIpNetDriver(ObjectInitializer)"

Remove TEnumAsByte<> (but not the type inside of it) in:
    - OnInput inside VRGripInterface.h
    - OnEndPlay inside VRGripScriptBase.h and its _Implementation version in the .cpp file
    - SetMobilityAllEvent inside DeerCPP.h and its _Implementation version in the .cpp file

Add this code underneath the struct in GripComponentEndPhysicsTickFunction.h:
template<>
struct TStructOpsTypeTraits<FGripComponentEndPhysicsTickFunction> : public TStructOpsTypeTraitsBase2<FGripComponentEndPhysicsTickFunction>
{
    enum
    {
        WithCopy = false
    };
};

Add the following 4 lines in the "Plugins" section in the generated "cyubeVR.uproject":
{
    "Name": "ChaosEditor",
    "Enabled": false
}

Packing for first time, you will get "game target not found" errors. Close Rider and UE. Then, copy and paste the cyubeVREditor.Target.cs file (inside Source folder) and name it cyubeVRGame.Target.cs. Then replace any mentions of "editor" and replace with "game" inside of this new file (or just put this code into the file):
using UnrealBuildTool;

public class cyubeVRGameTarget : TargetRules {
	public cyubeVRGameTarget(TargetInfo Target) : base(Target) {
		Type = TargetType.Game;
		DefaultBuildSettings = BuildSettingsVersion.V2;
		ExtraModuleNames.AddRange(new string[] {
			"cyubeVR",
		});
	}
}

If you get the "failed to create version memory for PCH" errors when trying to build or pack, do it again.