I think there's LOTS of media out there, but there doesn't seem to be easy ways to convert it.

There was probably a renaissance period when conversion equipment was being actively developed and available, but that time is probably gone. For example I think a good film scanner would be the Nikon Super Coolscan 8000 ED, but current state of the art falls far short. For film, vcr tapes and more we should be doing so much better.

I have old family super-8 films that are kind of convertible, but not the magnetic sound strip.

If you have something precious on home movie film, this lab in Burbank, CA that does a lot of the movies will have sometimes deals on film transfers for holidays, or you can call them for a quote. No relationship, but I did have some done and they were very good. https://www.pro8mm.com/

Wait, what's wrong with Cintel? I've not used it myself but got a really good impression back when I worked at BMD a few years back.