C:\Users\user>firefoxpwa site install https://x.com/manifest.json --profile 01K2GSX0N6J9BR5C7J5YA39VB7
04:57:57 [INFO] Installing the web app
04:57:57 [INFO] Downloading the web app manifest
04:57:58 [INFO] Parsing the web app manifest
04:57:58 [ERROR] Failed to parse web app manifest

Caused by:
    Provided unknown URL in invalid context

C:\Users\user>curl -s https://x.com/manifest.json
{"background_color":"#ffffff","categories":["social","news","magazines"],"description":"Get breaking news, politics, trending music, world events, sports scores, and the latest global news stories as they unfold - all with less data.","display":"standalone","gcm_sender_id":"49625052041","gcm_user_visible_only":true,"icons":[{"src":"https://abs.twimg.com/responsive-web/client-web-legacy/icon-default.522d363a.png","sizes":"192x192","type":"image/png"},{"src":"https://abs.twimg.com/responsive-web/client-web-legacy/icon-default-large.9ab12c3a.png","sizes":"512x512","type":"image/png"},{"purpose":"maskable","src":"https://abs.twimg.com/responsive-web/client-web-legacy/icon-default-maskable.bacea37a.png","sizes":"192x192","type":"image/png"},{"purpose":"maskable","src":"https://abs.twimg.com/responsive-web/client-web-legacy/icon-default-maskable-large.35928fda.png","sizes":"512x512","type":"image/png"}],"name":"X","screenshots":[{"sizes":"586x1041","type":"image/png"},{"sizes":"586x1041","type":"image/png"},{"sizes":"586x1041","type":"image/png"}],"share_target":{"action":"compose/tweet","enctype":"multipart/form-data","method":"POST","params":{"title":"title","text":"text","url":"url","files":[{"name":"externalMedia","accept":["image/jpeg","image/png","image/gif","video/quicktime","video/mp4"]}]}},"shortcuts":[{"name":"New post","url":"/compose/post?utm_source=jumplist&utm_medium=shortcut","icons":[{"type":"image/png","sizes":"192x192"}]},{"name":"Explore","url":"/explore?utm_source=jumplist&utm_medium=shortcut","icons":[{"type":"image/png","sizes":"192x192"}]},{"name":"Notifications","url":"/notifications?utm_source=jumplist&utm_medium=shortcut","icons":[{"type":"image/png","sizes":"192x192"}]},{"name":"Direct Messages","url":"/messages?utm_source=jumplist&utm_medium=shortcut","icons":[{"type":"image/png","sizes":"192x192"}]}],"short_name":"X","start_url":"https://x.com/?utm_source=homescreen&utm_medium=shortcut","theme_color":"#ffffff","scope":"/","android_package_name":"com.twitter.android","prefer_related_applications":true,"related_applications":[{"id":"com.twitter.android","platform":"play","url":"https://play.google.com/store/apps/details?id=com.twitter.android"}],"launch_handler":{"route_to":"existing-client","navigate_existing_client":"never"}}