Game won't start, stuck at splash screen

where exactly is hang ? Did you see already the blue-bar , around which prozent % ?

Otherwise a login-issue is common, think it is what @DensestSnail693 meant. So, did you tried already xbox relogin ( restart in middle ) ?

And may be… have you already tried the -FastLaunch option ?

PS:

yep, may be waits for more votes: Steam - Verify Integrity of Game Files Deletes All Content