Terry Davis tried to do for the PC with TempleOS what the C64's BASIC and KERNAL did for its hardware.

Terry was all the more a mad lad because he didn't get to create the hardware spec he was working with.

Could you imagine someone doing the same as Commodore did but starting with 64-bit era hardware?

Taking it another direction, there are free and paid "easy programming" platforms that provide a sandbox not unlike a modern version of what it was like to program a C64.

At a pinch, DOSBox and a copy of QBASIC might suffice.