It was no fun realizing after a few IRL visits that we really just didn't like each other unless careful email communications was our primary means of interaction.

With some folks the time it takes to write an email is all the filter is needed. Sometimes, though, it only takes 5 minutes IRL to realize that you only like the persons email - not the person, themselves.

I have acquaintances IRL, mostly from work. But my actual friends are people who I've never met face-to-face.

Are these really online friends if you are also recognizing them as real-life humans that exist in the same world you do and treat them like you would any other friend? Aside from maybe the Amish (and even that's questionable if you pay close enough attention to what they are hiding), there is almost nobody who doesn't communicate with friends using electronic devices. That is not a unique property.

"Online friend" only seems like a useful distinction if you truly think of them as a some kind of nebulous chat entity that comes to you via a connected device, where specific implementation details be it human, AI, space alien, or magical fairy doesn't play into the experience. Where if you eventually found out that it was actually ChatGPT on the other end you wouldn't be disappointed.