Routing device recommendation

I have been tasked to change our internet failover for a small site. We have 2 ISP lines, 2 LTE devices, and 2 separate internal networks. The powers that be would like a single device to manage the failover processes. So in theory if ISP line A goes down, I can route Internal network A out through LTE A or LTE B or even ISP B.

Each internal network has ~50 users. A device which can run on a BSD flavor or Linux distro would be nice to have scripts for the network changes. The failovers are not going to be seamless, but we have been on the wrong end of backhoes going through the ISP lines too many times for management's liking.

Any networking gurus have suggestions of hardware to consider/avoid?