The effort is almost the same, for reading OP_RETURN using bitcoin_cli the script would look very similar - i.e. it reads the bytes following "OP_RETURN" (i.e. "6a" in hex), for ordinals/inscriptions the script reads the bytes that follow "ord" (i.e. "6f7264" in hex) and it skips the "4d" bytes every 520 bytes...
Of course people will create viewers like mempool space that make this much easier. Same as they did for the data in witness/inscriptions: 
Transaction eadfab095bfe5bcfde6024126ef139ac0e98f19dcb4c8fc4e96bfa87cc39141e | Ordiscan
Explore ordinals and inscriptions on Bitcoin. Search and browse inscriptions, runes, rare sats, BRC-20, and more...
