There really aren't that many modem/router combos out there you can actually flash with open source firmware.
Router? Sure, no problem.
Modem? Outside of some very niche Fritzbox devices and others listed on OpenWRT Table of Hardware
There really just aren't that many.
So, fine. I will use a proprietary modem.
I will put it into bridge mode, let it decode the DSL analog signals into ethernet and feed that into a router of my choice.
Question is: Which modem?
I don't want two devices heating up my shelf. I just want a tiny modem that converts analog to digital into an RJ45 and then let's the router do its thing.
Does such a magical device exist, because my search on this front has proved largely fruitless
I do, they're all TP-Link devices which is a company that makes solid solid hardware, but they have sketchy links to foreign state cyber attacks[0]. I don't mind having a dumb switch from TP-Link that I can just network devices together locally and forbid it from having internet access via the router.
0: https://www.cnet.com/home/internet/tp-link-is-under-investigation-for-predatory-pricing-should-you-replace-your-router/
The so called investigation is political
TP-Link isn't perfect but they have decent security practices. (Unlike Cisco, Forinet and many other "premium" vendors)