I find it really surprising that SiFive doesn't come out with their own edition of this but with the latest cores, rather than a 3rd party with an old u74
Except expensive eval boards in very low volume, aimed at letting people who are licensing their cores to build a chip get a head start on software development while their own chip is under development -- much like Arm's $10,000 dev boards:
https://www.digikey.com/en/products/detail/arm/V2M-JUNO-0317...