If you’re using .fly.dev domains you should be able to use HTTPS so might be a matter of an URL being wrote wrong? Even if you use a custom domain, we offer HTTPS by setting certificates too.
If I’m understanding it correctly you don’t have a HTTP services section on your toml for minio so that could be a reason you’re not receiving HTTPS support.
One option to show files uploaded to mínio is to make it’s app public by adding http_services to the fly toml and ensuring you have public IPv6 and ipv4. That comes with concerns that someone could hack into your mínio instance if they know how to exploit it but definitely makes things easier.
Another option you could do is keep mínio private and route certain requests to it using fly replay. That’s takes some chore work on your app. Here’s an example: