Wow, I had no idea this would go around so fast. I was shooting to get the portable done as quickly as possible, and so had to settle for no bankswitching.
I do have plans to make a portable using an original 2600 4-switch board, and a new multicart loading games off SD cards with the most common F8/F6 bankswitching.
However that will have to wait until I can save up some more money to get a PCB made for that.
If anyone wants to see their 2k/4k game running on this (and assuming it doesn't use illegal opcodes that foul up the FB2) I'll be happy to run it