On top of the other posts, archive.org is involved in a major lawsuit and its theoretically possible it would be forced to shut down depending on how big the copyright violation fines end up being, among other things.

this isn’t very reliable as it relies on someone (be it real person or a bot) to archive the specific post / answer.
if your post / answer gets in the front page or all or popular, there might be a chance, but if it died in ‘New’ ? fat chance there’s an archive for it.

There’s an app I’ve come to like called sharchive. Can just share whatever link I want to open in archive.org or archive.is and I use it a lot for pay walled sites.

Simplest way for managing reddit links encountered in search I’ve found is just getting Stealth from the f-droid store and set it to use a teddit instance and open reddit links by default. No ads. Uses a reddit front end so less info for Reddit too over visiting it directly and times when you click search results without thinking.