It's actually pretty easy to port C64 software - both Assembly and BASIC. It uses the exact same BASIC and same processor family as the Commodore 64, NES, Apple II and many others.
Memory map, graphics and sound are the biggest challenges in porting because those are different. But code to translate between these will get better and better. Lots of ports from other systems already.
Somewhere I saw a project where someone made a new motherboard for a 99/4A so it would fit in a mini-itx case and tweaked the ROM so you could add an external PS/2 keyboard. After buying the board, you bought an original 99/4, yanked the chips out and used them to populate the new board.
I don't know if that really counts as "new hardware" but it was an interesting idea and was supposedly very compatible.
If you are looking for a "retroremake" of the C64 that's actually an ARM chip running inside a functional C64 breadbin case, with working keyboard, I recommend TheC64 [1] (full size version, not the Mini which is just a game console).
You can program in basic and assembly language with it, plus it has HDMI output so no additional cables or adapters required to connect it to an LCD.
Internally it's running a modified version of VICE.
The Mega65 is actually a realisation of an unreleased model that only made it to prototype stage back in the day, but yes, it is backwards-compatible with the C64.
https://www.commanderx16.com/