You can switch in dual RISC-V cores in place of the dual ARM cores if you're feeling adventurous, but I think I'll stay with the better-known and presumably better-performing ARM cores.
Anyway, there are a whole lot of useful realtime I/O features in the RP2350 that should enable me to wire up a portion of the GPIOs to all the non-voltage pins of the 65C816 and have it provide the entire address space and emulate an Apple IIGS or anything else I want, in 32-bit ARM code, running on FreeRTOS.