IIRC you can’t even read a single post without an account, it is equivalent to posting a link to a private Facebook group or whatever from an outsider point of view.
You can see the last few posts of an account [1], and the contents of a single posts, but minimal or no comments [2]. Videos play after dismissing the login popup.
I only get "See this post in the app" with "Use the app to view all comments and discover more posts." with only an "Open X" button in that dialogue.
There is no button to disable this. I can only see the text by using "Page Zoom" buttons on my phone, so it's really not worth it.
* Looked at the top-right corner of that popup.
* Then, scan upwards from that corner, maybe 1cm above it
That’s where the x to close it is, for me. I’m not sure if it is screen specific or what, if it is a bug, etc. It doesn’t seem like a UI anyone would build intentionally but then, who knows?