With backups two is one and one is none, so you are very much in a right track. Personally I have my stuff running on proxmox VMs with a proxmox backup server (VM as well) storing backups to Hetzner Storagebox. I’m planning to set up a another host in garage to have “local” backups too, as mine is detached as well the risk of both going up in flames in event of fire is pretty low. However, a voltage spike due to lightning on the grid or something else might blow up both hosts so that’s a threat model to be aware of. Also if your connection to garage is over copper it can cause other problems, fibre or wireless is highly recommended.

With backups it’s largely about the bandwidth available. I personally have enough so uploading to cloud is not an issue, but backing up a terabyte of data over 10Mbps connection might not work out at all.

For more info search for 3-2-1 strategy, that should give you plenty of ideas what you need to think about and what are industry best practises about making sure backups are in order.