Some quick feedback:

• Alignment worked as expected
• Loading the logo block after already uploading an image worked as expected (the logo was pre-loaded when I did it the second time)
• There's no logo icon next to "Site Logo" there in the middle (just under the logo in the screenshot above)
• Resizing the image didn't seem to work immediately after I uploaded the image. I had to delete the block then add it again to get the resizing to work. I believe this is due to the fact that it was in edit mode (See screenshot above). But I'm not sure this is easy to grok.
• The "Upload" option didn't work for me. I selected a file and nothing happened. I had to select "Media Library" and upload my logo there.
• The resizing option in the sidebar is still set to % instead of px (guessing this is still being worked on).

Another round of testing. Here's what I found:

Block logo

• The solid icon style with the white star and the solid grey bg does not match up very well with the outline style of the other block icons (See: https://cl.ly/ef39e6725bc6). Can we swap this out for this SVG: https://d1czrtm2mp3lak.cloudfront.net/items/1R1D3s182R2i0v0S3I3e/logo.svg

Uploading

• I don't believe SVG files are allowed. When I try and upload one, nothing happens: https://cl.ly/38c8537baed6 Can we filter which file types are acceptable? The image block displays an inline error: https://cl.ly/e0cde373d136
• The image block shows a preview and a little loader icon immediately after you upload an image: https://cl.ly/242bfe94425e. The logo block just pauses for a long time and then appears once the file has been uploaded: https://cl.ly/fefa1ebbe185 Can we adopt the same loading state as the image block?

Resizing:

• Upon initial upload, the resize handles are not in the right place: https://cl.ly/1ba1478969da If you click then, they snap to the image. I noticed that if you upload the same image again, that this will not happen, so you'll need to use a new image. Here's the one I used: https://d1czrtm2mp3lak.cloudfront.net/items/3t1e2a1K392F3i1J2R1G/MyLogo.png
• Remove a logo block, then add it again and the logo dimensions are SUPER tiny: https://cl.ly/56df97dadc5f If you click the resize handle it magically resizes.
• When I edit a logo and select another image from the media library, the resize handles are all off. Clicking them does not help: https://cl.ly/a36aff132a54 My assumption is that they are stuck on the size of the previous logo.

Alignment

• Alignment within the image block seems to take place all within the bounds of the primary editor container: https://cl.ly/b181f5f6fd1a With the logo block the alignment options appear to take you outside of this container: https://cl.ly/1a5444bdaef8 It's not clear to me whether that was intentional.

Duplicate

• Creating a duplicate of the logo block creates a blank block container until you click outside, upon which the logo shows: https://cl.ly/78e6e5eb7927

Edit as HTML

• Edit as HTML produces no markup: https://cl.ly/63812a231d91 For comparison,. the image block produces the following markup: https://cl.ly/fb623fc4980f

Reusable Block

• Turning the logo block into a reusable block has some bugs: https://cl.ly/f855268e4513 At first it doesn't show up, until you click around. When you try and reuse it, the logo does not show up at all, despite clicking around. To contrast, here's what it looks like for the image block: https://cl.ly/e88bbbd27803

Hopefully that is helpful. Sorry for the big ole list! 😬

@paaljoachim I think I've addressed all the concerns above, so this is ready for another review :)

A more unique icon and more integrated with the latest library and styles might help with consistency and identification.
Perhaps a flag. Available here.

An alt logo in case it holds the toolbar with a better hierarchy.

The first one was