are there any plans for rockbox to support risc-v, if so maybe this would be viable? - https://www.gigadevice.com/product/mcu/risc-v/gd32vw553kmq7
Rockbox has been natively ported to four distinct CPU architectures, and the hosted port can run on anything that is capable of running Linux or SDL. So there's no inherent reason why a RISC-V port can't be done, other than the willingness of a suitably skilled someone to undertake the effort.
However, it's not going to be to that particular gigadevice SoC - It only has 320KB of RAM, placing it in the same general class of shovelware SoCs like the RKNano and ATJ212x/215x/216x series, sporting an order of magnitude less RAM than is needed for something that would have the features users expect from something called "rockbox".
While we already support slightly-feature-limited low-res monochrome targets with only 2MB of RAM, The full feature set (with a color screen) requires at least 4MB of RAM, and ideally over 8MB for the full set of plugins.