Just go to a vendor and use edizon to search for the current amount as a U32, sell something, search for the new amount, keep repeating until you find the value(s).
Not sure about other models of Pi4 but the Pi 4 B with 8GBs OCed to 2Ghz handles PSP really great except like 1 game I found and it is playable it just looks bad lol Motor Storm Arctic something or other.