I’m about to buy a WIFI 6 WRT/Open Source router and need recommendations, explanations and comments.

I’ve read the online articles. I need to hear from someone who has one already.

I have an Airport Extreme and a Time Machine server. I have a Spectrum internet that constantly acts up. I don't know why I can't use either of mine to replace Spectrum's but it's not working. So when I buy a new one I want to plan for the future even if I have no immediate need. For example, once the stimulus check reaches me a big chunk goes to the mac mini M1. It's WIFI6 so the new router needs accommodate it. I'm a network nutso too. I started with twisted pair and then grinos for packet on two meter. So I want to have as much or little control over settings ergo WRT or at least open source router control.

Now the question for you and Dan: what inexpensive WIFI6 (meaning mac mini compatible) and open source os would you recommend ?