Yes, lots of Intel and AMD based SBCs have SO-DIMM slots, but you'll have to accept the 3.5" format.

Regarding RISC-V SBCs, there was serious consideration to release the Milk-V Oasis with SG2380 and LPCAMM2. But this didn't work out as the SG2380 was held up by geopolitical issues.

Still so mad about that