For me, it's not enough to verify the integrity of an ISO – I also have to verify its authenticity (or at least verify the checksum file) with GPG. I don't know why, but just need to see that "Good signature" message before I feel safe installing Linux.
I notice, though, that the download pages of some prominent distros (Pop_OS!, openSUSE, etc) just give you a checksum, probably because they feel that anything else is unnecessary. This makes me shy away from installing them, which is a shame because I'd like to give some of those distros a try on bare metal.
Am I being paranoid when it comes to installing Linux?
Going a little overboard there in my opinion. If one of the major distributions would catch something sketchy, a whole bunch of tech savy would be all over it in no time.