You may want to look into an object storage solution with an S3 compatible API. Then you have something extremely common and relatively standard. The museums can upload using many many tools, from command line to Software libraries to graphical user interfaces.

A few links if you want to look into it:

- https://en.m.wikipedia.org/wiki/Object_storage

- https://min.io/

- https://docs.ceph.com/en/latest/radosgw/s3/

- https://aws.amazon.com/s3/

- https://cyberduck.io/s3/

- https://winscp.net/eng/docs/s3