I am doing this right now. A starlink CPE is a fairly ordinary DIA link that exists in cgnat space from the perspective of whatever router you plug into it. The starlink indoor 'router' is optional.
Whatever you plug into the high power PoE injector will be given a DHCP lease and a default route out to the world. People who don't want to DIY a dual-WAN solution with their own Linux box or pfsense or similar can use things like peplink routers.
In difficult to reach places in the world I can see starlink with a low-bandwidth traditional VSAT link as backup/failover as a fairly common configuration. Or starlink as primary and local HSPA+/HSDPA/LTE (whatever 3GPP related) as a failover.