Shared Internet connections

We are in the process of building a libre router network in our area and wondered if we can have mulitiple shared broadband connections? So for example we setup 10 libre routers all within 100 meters from each other to create a large mesh network for phone users and laptop users.
But can every libre router node share out their broadband and use Qos to control how much bandwidth they want to share?

You mean, each LR in the network having a different internet gateway through, let’s say, their wan port ?

Yes that’s correct. Is this possible, so that wherever the user is they will access whichever gateway is available?

Yes, it’s possible. LibreRouterOS has the same support for QoS than plain OpenWRT. See [OpenWrt Wiki] Traffic shaping for reference.
Although the routing protocol will not differentiate between gateways with restricted and unrestricted bandwidth.