No worries!

I think if I was going to read manga digitally I'd be reaching for a tablet to do so because they can display colour and the screens are generally a lot bigger and can handle zooming if needed. Apparently the subreddit r/MangaPiracy has some good links but I haven't looked into it because I'm not into manga. Obviously you can run a tablet as an e-reader too and the added screen size might be a benefit here.

I get what you mean about screen size being small.

I prefer larger text myself and that's actually why I prefer e-readers (aside from the perks of piracy of course) because you are virtually unlimited in how large you can make the font size; since the screen is effectively limitless, you can either infinite-scroll as you read line by line or you can just tap ahead to the next page as needed.

Obviously different devices meet different needs.

If I was looking at reading PDFs and .cbz sorts of files, a tablet is absolutely the way to go.

If I wanted large print size then a phone is good and an e-reader is better but you're limited to epub and mobi files (PDFs are possible on a phone but it's generally a bit hard going to read an entire PDF of a book on a phone.)

If you want an all-arounder then you can't go past a tablet though.

One of the dirty secrets of the tech industry is that tablets and e-readers really don't need to be released on a schedule like iPhones do. If it's just for displaying text or PDFs then you can grab last season's model on clearance, a second hand device, or a brand new low-end device and it'll work just fine for your purposes.

(I'd steer clear of Kindles tbh. They run surprisingly buggy software that struggles with producing text and you have to go through workarounds if you sideload most of your books so it's much better to get something like a Kobo tbh.)