Creating a passkey generally won't erase your password, no. Using a passkey generally requres a password manager or yubikey, so you can set that up on the other device and use the same passkey.
Answering respectively: it's lost; no; same way you reset passwords; depends what you mean "what if" - if your passwors manager is already authenticated and doesn't require reauthentication, then yes, it could be used to login.
And to answer your additional question, yes, I suppose you would either need to install your password manager or use whatever alternative 2FA login you have.
I don't think quality is really much of a concern for the majority of people, only enthusiasts. I suspect, analagous to 128 kbps opus (on youtube music), most people can't really tell the difference between a 1080p bitstarved stream and a 4k bluray rip.
The library for the music streaming platforms is much bigger than for films, of course (about 250 million for Spotify), but there's also a much lower barrier of entry. So perhaps the higher work needed to produce a film necessitates more profit, to a degree that only the fragmented streaming platforms can fulfill. After all, netflix started making originals to counter studios launching their own streaming platforms to raise profit margins, and pulling their content off netflix.
Do you think the difference between film piracy and music piracy is inherent, due to the differences between film and music; or is there some alternative reality where we ended up with a one-stop shop for films, as well?
For the history of music piracy, I found" How Music Got Free: The End of an Industry, the Turn of the Century, and the Patient Zero of Piracy" was a good book to read.
How far back do we take it? In pre-historic times, did people crawl accross the ground to better enjoy it?
There's little correlation between people complaining about something being better in the good old days, and it actualli being better. Not for no reason is "rose-tinted glasses" an expression.
Due to EU regulation, you can use a different browser engine in the EU (and I think Japan too), but thus far none have been developed (it's too much work to maintain two versions of the browser).
There's garden path sentences, where the sentence is phrased in such a way as to cause you to misparse the sentence when you first read (e.g. "The old man the boat"); but those typically confuse humans (I'm not sure how effective they are on LLMs).