Tbh I sometimes sshfs mount a vps onto a home machine but doing it the other way around doesn't seem worthwhile. The idea of a vps is that it's in a data center, has tons of bandwidth, backup power, you can set up a failover scheme if you need high availability, etc. Stuff like media is on your home server so you can use it locally, and maybe it's backed up remotely just in case, but doesn't need to be live mounted. That said, I'm used to home internet being unreliable compared to VPS, so mounting it to a vps sounds flaky.
If you want more storage on your vps, just get a bigger one, I would say. Or if you want tons of remote storage, get something with better connectivity.