Personally I think the LicheeRV nano on SG2002 is worth the investment of 15-20 bucks.
This thing has USB OTG, multiple usable GPIO and can be flashed via microSD and has a display out with touch support.
I was in the process on building a little iPod Nano clone[1] with Rust / Slint but i was too busy for a while, yet I plan to get back to it in the future. Unfortunately the sg2002 image has no CPU governor yet.
Maybe I switch to the tinyembedded dual with a custom PCB to save power[2].
It's taken many years but Sophgo has got a lot of their drivers into the mainline kernel and i do commend them for that.
Unfortunately, to my knowledge there is no "official" buildroot image for the LicheeRV Nano that supports a Kernel higher than 5.x, although 7.x would bring native support for many features, likely the cpu governor.
However, there is also still a proprietary bootloader blob that has to be included, but still: I like the device and it's hardware... it could have better docs though.
I wrote some best practise, but a lot of thing are still missing: https://github.com/scpcom/LicheeSG-Nano-Build/blob/develop/b...
A newer project might be more successful on that: https://github.com/lone0/buildroot-external-licheervnano
No official images, no. I have a personal one: https://github.com/queenkjuul/milkv-duo-ubuntu
But it isn't generalized.
It also doesn't support the weird sophgo "media engine" which is the big roadblock, but the code might help you.
There's been updates since i published that, though.
There is someone out there with an open source bootloader blob, i think i saw it on the milk-v forums can't remember the link