How exactly would I go about avoiding consumer routers when every provider in my area forces me to get some kind of modem with built in router and wifi?
If the router is also used as a media-convertor (upstream is Fiber or DSL or coax), they should be able to set it to "bridging mode", where it will function as a Layer2 device (switch), thus allowing the customer to use their own Layer3 device (router).
It is a ridiculous situation, but I actually have our provider-provided router connected straight into a real firewall, and that in turn connected to a switch which in turn has the wifi base stations connected to it.
This means that if the first router is compromised there is a chance it won't penetrate the household, but of course the first router could still be used e.g. as part of a botnet by an attacker.