To add to that, they are very open about inquiries from legal authorities, see their yearly Transparency Reports:

Not all the enquiries we receive are legal, and our data protection officer will critically assess every single request in order to make sure it is in line with the requirements of the law. If there are any doubts about the legality of a request, our specialised lawyers will be consulted. If a request is formally and legally correct, we will service it, otherwise it will be rejected.

…BUT E-Mail is an insecure form of communication by default, so you should definitely look into PGP encryption, see Privacy Guides - Email Security.

Taiga (https://taiga.io/) could be what you’re seeking.

Sorry, I’m not the creator of the app, but they have a way to contribute via Github: https://github.com/K-Robin/GoEuropean/blob/main/CONTRIBUTING.md

Yeah… we’ll get there eventually, babysteps! If you want to give the dev (u/KRobinDev) a nudge in the right direction, try your luck; I don’t have an account.

Important addition: You’ll have to set browser.urlbar.update2.engineAliasRefresh to true in about:config to see the option to add search engines via URL. Otherwise you’ll just see the option to remove them and a link to the add-ons page.