I honestly spent like a week, outlining what I would need to build a FOSS phone, on RISCV.

current revision could do it. it would be a bit slow, but it's possible...

all was good till I hit two hardware bottlenecks.

1. GPU: unlike ARM which several manufacturers have 2d/3d accelerators. RiscV really doesn't have that. all current implementations are primitive... (I have a Spacemit K1 SOC, I have been prototyping with and it's entirely Vulkan based and stuck in mid stages of MESA development. so *Gl in Vulkan wrappers are broken... GUIs perform like a m68k machine from 1988...)

2. this is the big one, Modems. there is only two suppliers and both are vendor locked. they won't provide hardware to ANYONE without a contract.

this is why 5g USB/PCI-E modems don't exist. there is a monopoly no one is talking about...

until these two points are addressed a foss phone is not possible. not even close. ~ even if you damage control on software (aosp) and some how convince amd/Intel to sell you chips for GPU on a PCIe lane sharing ram...

your still stuck on the modem. some one needs to get the ball rolling on a monopoly suit against the big two.