You can use this in your A500:
https://amigastore.eu/682-keyboard-m...00-1200.html#/
or this:
https://www.ebay.com/itm/HARD-MEMBRA...0AAOSwS4he1AFB
I do have couple keyboard to compare, and I noticed that some A2000 keyboards have same pcb board as A500. The A2000 uses 4pins ti DIN connector, the A500 6pins to motherboard connector.
I think it's easier to get the membrane.