Is there any way to backup (& restore) the D365 Fundraising and Engagement environment and data?
Yes it is internal backup and you can restore to a production environment, first switch it to a sandbox environment. See learn.microsoft.com/.../switch-environment.
Thanks. As I understand from reading the link, this is an internal backup within D365 (is that correct?) not an 'off-site' or out-of-system backup per se. Also, there is a curious statement "Only sandbox environments can be restored to", which I read to mean that production environments, if corrupted, cannot be restored.
Yes there is there are some Backup capabilities.
More information on: learn.microsoft.com/.../backup-restore-environments
but please make sure to read the entire documentation, as there are some limitations, and the backup doesn't last forever.