I'll remember well UCSD Pascal https://en.wikipedia.org/wiki/UCSD_Pascal especially as compiling on a system with one floppy drive required 5-6 changes of the floppy disk even for a 'hello world'. So one would think twice before starting the compiler only to find a simple syntax error after a minute or two. :)

Absolutely true, there were and are MANY compilers for the 6502.

However, the 6502 was a challenge to implement high-level languages on, IF you also wanted speed and small code size. But since the 6502s were slow compared to modern chips, and could only address 64KiB directly, you typically also wanted speed and small size.

I posted some links to some approaches here: https://dwheeler.com/6502/

Sure...they were amazingly widespread machines back in the day so lots of people took a whack at a 6502 compiler (at college if nothing else). But how many could take on non-trivial programs and emit code that would be considered production level? I know Apple Pascal was supposed to be pretty good, but what else?