This BananaPi RISC-V router board is officially supported in OpenWRT https://docs.banana-pi.org/en/BPI-RV2/BananaPi_BPI-RV2 and is very affordable. While not as powerful than the Spacemit K1 and having much less RAM, it works rather well and is very stable. Different metal cases available. POE option exist for the board as well.

Orange Pi RV2 is very similar in spec to this star9.com router.