Work with informationsecurity and GDPR. And know as a fact that many danish municipalities which administrate the libraries are using, and are happy with, Linux as public facing citizen PC's in libraries.
They use OS2borgerPC, which translates to OS2citizenPC which is maintained and supported by the danish company Magenta. But it's open source, so if you are in another country you could just use it - or better, give Magenta a call. They're great and very reseaonable.
Magenta: https://www.magenta.dk/en/ OS2borgerPC on github: https://github.com/OS2borgerPC
Maybe not quite on the spot, but a Storage Share (hosted nextcloud) from Hetzner might be an option.
Bonus features and info: You can also share other files, location, calendars, contacts etc. They have a compliant data protection agreement, and are fully GDPR compliant.
Hetzner Storage Share: https://www.hetzner.com/storage/storage-share