They look similar, but K210 is actually a quite special chip. It has more horsepower than current ESP32s, has dual RISCV(open source instruction set) cores running at 400MHz and also some hardware acceleration for video processing and SHA256. Keith, from SeedSigner is on an effort to run SeedSigner code on ESP32s, but it is quite challenging, as they run at 240MHz and lack of fast video buffers. ESP32 manufacturer, Espressif, now seems to be going in direction of RISCV cores, next chips will be more suitable to run optical signers.

You can easily find Amigos on Aliexpress, probably on Digikey, Mouser, etc. too