Yes, I was actually thinking about this as a product, but unfortunately regulations are tricky (for a commercial service). However, it's relatively easy to setup. The cheapest and most affordable way to do it is any MikroTik device. RouterOS can set any number of ports as WAN's, and do multiple VPN connections with bonding support and full routing exposure. I would say that two $50 cheapest MikroTik boxes could make this setup easily. I have experimented on their carrier grade CCR models, but in basic, same RouterOS is on all of their devices with same feature set. There's no need for any license level that does not come with their cheapest offering.

Here's one fully suitable to support home setup according to scheme above:
https://mikrotik.com/product/hap_ac2

It can even expose the VPN bonding to home WiFi