SailfishOS is fully functional and usable if you do not need any playstore-only apps. Even then they have now implemented microg in v5.0

Have you checked out Buypass? Norwegian alternative to Let’s Encrypt. I have been meaning to try it, should be drop in replacement for LE witch acme.

Edit: Here is a link https://european-alternatives.eu/product/buypass-go-ssl

I’ve been using it lately, I like it very much. They use iTunes as search provider by default.