good news: yes it exists. someone has it.
better news: the transcription is by Reinecke (which tend to be better then Hummel, who did not do 488-don't get me wrong hummel is amazing but i have read that his transcriiptions are needlessly difficult in spots with extra unneccessary ornamentation)
bad news: i don't have it. a piano god much more knowledgeable than i was consulted on this and his words were:
"...Reinecke arranged all of Mozart's piano concertos for piano solo,
and they were published in 4 volumes by Breitkopf and Hartel.
K488 in is vol.4 (pl. no. VA427), which is available from Berlin State Library.
Generally speaking, this edition seems even harder to find than
the Ruthardt arrangements of 8 of the piano concertos, including
K488, which was published by Peters (pl. no. 8163)...."
entry:
https://musikipac.staatsbibliothek-berlin.de/ipac_musik/catalog/main?cn=S&lin=S4700001&rin=S4700140&ro=-1&css=11&cop=:osyi do have one of the reinecke concert transcriptions, k 238 in b flat though both the 2h solo ver and the two piano ver in a russian edition, im happy to furnish that one if you like but i don't know if you needed 488 in particular or were just looking for a mozart concerto . hopefully it helps point you in the right direction. i wish i could swing this one but i speak from experience, some of the reinecke scores are incredibly difficult to find. i had a super freakin difficult time finding op 251 in complete form (not just no 3 as it is currently published but the version w 1 and 2). someone over there had to find it scan it and provide it to me, and it was only through happy coincidence that this individual had doen so years ago and happened to furnish me with the score. so unfortunately i cannot relate any contacts or methods of how to actually get eyes on the library copy.
