You can use these providers: https://yctct.com/email-providers
A couple of options:
Encrypt your email communication - see: https://emailselfdefense.fsf.org/en/
Encrypt files - see: https://www.gnupg.org/gph/en/manual.html#AEN111
See: https://yctct.com/password-guidelines
Use a repository to collaborate and keep track of the work of your organisation, for example: https://codeberg.org which is an instance of copyleft-licensed software Forgejo.
See: https://yctct.com/jitsi
https://ryf.fsf.org/products