Garage is really good for core S3, the only thing I ran into was it didn't support object tagging. It could be considered maybe a more esoteric corner of the S3 api, but minio does support it. Especially if you're just mapping for a test api, object tagging is most likely an unneeded feature anyway.
It's a "Misc" endpoint in the Garage docs here: https://garagehq.deuxfleurs.fr/documentation/reference-manua...