Well, it's not really clear-cut, which is part of my point, but probably the 2 most significant people I could think of would be Babbage and Turing, both of whom were English. Definitely could make arguments about what is or isn't considered a 'computer', to the point where it's fuzzy, but regardless of how you look at it, 'computers were invented in America' is rather a stretch.
To say I'm annoyed would be very much overstating it, just a (very minor) eye-roll at one small line in a generally very good article. Just the bit quoted:
currency symbols other than the $ (kind of tells you who invented computers, doesn’t it?)
So they could also be attributing it to some other country that uses $ for their currency, which is a few, but it seems most likely to be suggesting USD.
Onlyoffice does now have an ARM version, I run it on a raspberry pi 4 (integrated with seafile), and it works fairly well. Can't vouch for how much power it needs, to say if a pi 3b+ will be enough, though. Pretty sure it's lighter than collabora, since more is done on the client side.
I agree with the other commenter that suggested cryptpad, though. If all you're after is a Google docs like collaborative experience, cryptpad is brilliant, and much more resource friendly. (The office editor it uses is also a slightly modified Onlyoffice, so almost exactly the same feature set)
Who wants to tell the author that not everything was invented in the US? (And computers certainly weren't)