Hey there, sorry you haven’t heard from support yet. They are a little busy at the moment but are working through tickets as fast as they can.
I’m just on my phone this morning and I gave this thread some searches for suggestions and it looks like you’ve tried most things that would help.
I did notice that your steam repair always finds 1.3gb to repair. Almost like something is automatically removing 1.3gb of files or maybe is attempting to edit files in a protected folder.
I’m not sure exactly what’s happening but given the consistent repair size and the startup crashes, that’s where I would look first.
I’m sorry if this has already been suggested but is it possible that your antivirus program is finding a false positive and deleting a chunk of files? It should have a record of which files it has expired recently. You can also set the install directory as an ignored folder temporarily to test. I would still do one more validation after turning it off.
Startup crashes have also been linked to corrupted graphics ini files. This most often happens when they are manually edited.
I don’t generally do troubleshooting stuff so I’m not up on the most current common issues so someone else might be able to help better but this is what I’ve got for ya.