Comment by UweSchmidt

I wouldn't go for the cheapest price, I'd go to some established place in your jurisdiction with a wider product range and size, that targets small businesses. You have a chance to get some useful hotline, and things can be 'integrated' and are more likely to work, i.e. host your website - book the domain example.com - book a managed nextcloud and have it be at cloud.example.com etc.

Their email service is likely to have some credibility from the global anti-spam force. They probably have the budget for best practices and reasonable security. As you mention .de domains: The online legal text generators for Impressum/Datenschutzerklärung are likely to have the correct text fragments to use for larger vendors. Overall they just have to uphold some level of reputation I hope.

Example: ionos.de