I recommend you look into restic which is a incremental backup tool that can end-to-end encryption the store so that you do not need to trust your storage provider.
Restic can also work with a NAS at your friend but it might turn out it is cheaper to get something like a backblaze B2 Cloud or wasabi S3 storage where a terabyte is like around 6$ a month only!
I recommend you look into
resticwhich is a incremental backup tool that can end-to-end encryption the store so that you do not need to trust your storage provider.Restic can also work with a NAS at your friend but it might turn out it is cheaper to get something like a backblaze B2 Cloud or wasabi S3 storage where a terabyte is like around 6$ a month only!