uppen + an, uppan [OE]
upon [MI]
upón
https://www.etymonline.com/word/upon#etymonline_v_4539
https://www.etymonline.com/word/on#etymonline_v_7013
https://www.etymonline.com/word/up#etymonline_v_4533
https://quod.lib.umich.edu/m/middle-english-dictionary/dictionary/MED50463
https://bosworthtoller.com/34071