Convert your ACNH base game to NSP using NSC_Builder , then apply the update via Ryujinx's "Install Firmware/Update to NAND" option.
ACNH updates are in the same way other Switch games are. You cannot always skip versions. Try this sequence if you have the 206 error: animal crossing new horizons nspupdate 206
While Nintendo did not publicly detail the fixes, data miners and community reports identified several major improvements: Convert your ACNH base game to NSP using