Yep, for ex: we use the exact same code to get/put files to DigitalOcean Spaces... the only thing that changes is a config value for the S3 endpoint. S3 is basi

Yep, for ex: we use the exact same code to get/put files to DigitalOcean Spaces... the only thing that changes is a config value for the S3 endpoint. S3 is basically an open standard. The only vendor lock-in would be the time/money it takes to copy your data out of S3, but that's the same for anywhere you store your data... even when self-hosting.