Support for Raspberry Pi Pico 2 aka RP235x

I'm fairly far along porting Hubris to a Raspberry Pico 2 board (specifically a W, but that's "just" a Pico 2 with an SPI-attached radio), and want to check in to see if contributing such a port would be welcome. I understand that Hubris is not intended to be all things to all people, but the Pico 2 seems potentially relevant because:

• the RP235x chips are veeeerrrry popular by dint of being supported by the RPi foundation
• the Cortex-M33 has an MMU, which the RP2040 lacks
• a (now-outdated, draft) RP2040 port exists
• there are interesting secure boot features that may be appealing to Hubris users
• it's possibly a good jumping-off point for RISC-V and multi-core support to already have a cheap board supported

There are a few questions/concerns that have arisen as I've worked:

• I've got most of a porting guide doc in my head - do you want one?
• It's basically necessary to build apps/tasks in a fork anyway; should ports stay in forks as a rule? (e.g. here's hubris-flipper). Being able to build apps and tasks out-of-tree would be cool.
• Peripheral abstractions can range from vry smol to exceptionally exhaustive. The e.g. LPC55 abstractions appear to be fairly extensive; how much of the RP235x datasheet should be encoded in this repository given that y'all don't use it?

Start with the linked drv/rp2040-sys-api/src/lib.rs port and compare its scope with drv/lpc55-gpio-api/src/lib.rs. Before coding, clarify whether an in-repository RP235x port, a porting guide, out-of-tree app support, and which peripheral abstractions are wanted; done means an agreed contribution scope and accepted porting approach.