I use Arq[1] for backing up my Mac. It's also available on Windows, but not Linux. However, it does allow you to back up to Linux, via SFTP. It also supports S3 and a few other cloud services.
It does cost. You can either pay for a subscription to use their servers, similar to Backblaze, etc, or you can pay $40 (this is what I did) for the stand-alone app. Personally I back my Macbook up to S3 - it costs me less than $5/month. I've been using it for a couple of years now and it gets regular updates and has saved the day for me more than a few times.
That sounds like a good possible solution. Online backups are not an option for me, due to internet limitations, but paid app with open source restore tool is an acceptable solution. At least that way I am not going to be stuck with no way to retrieve my files in case the company ever goes out of business or something like that. I wish there was a way to make it run in powernap, like Time Machine does. I was even considering using TM with a network drive. It's not terribly difficult to setup, you just need to setup AFS I believe , and set a few flags. I have done this before. But TM is annoyingly not configurable and insists on "backing" things up locally until it can offload the backup to the server.
It does cost. You can either pay for a subscription to use their servers, similar to Backblaze, etc, or you can pay $40 (this is what I did) for the stand-alone app. Personally I back my Macbook up to S3 - it costs me less than $5/month. I've been using it for a couple of years now and it gets regular updates and has saved the day for me more than a few times.
[1] https://www.arqbackup.com/