I don't know any non-profit organisation, but one of them offer free plans and as far as I know some european countries directly offer services to sign documents for their citizens. For example Austria with handy-signatur.at and the Digitales Amt app. (most of it only for Austrians and/or in German language)
Thanks for the constructive criticism! Hetzner is now listed. (https://european-alternatives.eu/product/hetzner) Since Hetzner mainly provides virtual servers, I have created a separate category for them. I just wrote down SAP, here I still have to think of a suitable category.
I run the site and as many things in life this site is a work in progress. I got many suggestions for new services in the last days, so there will be many more services in the future.
Hosting Checker not only checks websites, but which providers are used for email and name servers.