To help someone who wants to identify and quantify the pitch ranges of songs, I wonder whether the printed editions of pop songs are commonly in the original key.
I think it depends a little on the instruments - often guitar-based bands tune down to assist the vocalist and so the written sheet music is shown in (for example) E flat whereas it would actually be easier to copy them and tune down a semitone and so play "open" shapes. E flat/A flat/ Dflat chord shapes are not easy except as barre and its often easy to play with Open E/A/D chord shapes but detuned to E flat. Its not quite your question but it took me a long while to realise that this was happening and why some transcribed music was so hard to play as per the sheet music.
To answer your actual question, I think keyboard music is usually in the original key.
This comes back to the recurring theme of "online music sucks". Not always, of course, but changing the key is very common online for pop songs, for whatever reason. Guitar music is the most notorious for doing this, and I'm thinking keyboard music is nusually more adherent to the original key. Consider that anything that is online is usually not the greatest source for determining the key, aside from the source material itself.
Sheet piano music of popular songs (e.g. what you'd get from Hal Leonard) is almost always reduced to 2 or 3 sharps or flats. If you look at, say, a vocal score to a Broadway show you are likely to see more flats and sharps while the popular versions will be transposed to C, F, Bflat, EFlat.
Unless the original was in a one of these "simpler" keys, the popular sheet music version is not likely to be in the same key.