This is a 6502 emulator for the Raspberry Pi Pico
You can interact with it via its USB serial connection.
It emulates a 65C02 processor so that Taliforth can run on it.
Most of the 6502 emulation code is from this codegolf answer with some additions to add 65C02 instructions and adressing modes.
The interaction with your 6502 programs is extremely simple: any write to address $F001 will appear on the serial console, and you can read from $F004 to see if a character is available from serial. This means that obviously your own programs must not tough these two addresses for anything other than input/output.