You have some makers like Turris and GL.iNet that ship their devices with some customised flavor of OpenWRT. I just wander through OpenWRT's table of hardware, looking what devices fulfill my needs and are available in my country.
In the forums [0](Discourse alert) you have many threads with suggestions, too!
The WRT1200AC family is not well supported. The Ethernet part should work fine, but the Wifi is unsupported since some years now, see here the repository: https://github.com/kaloz/mwlwifi The vendors are not interested in this hardware any more, but they have very good marketing and sales. Linksys and Marvell also did not really support the OpenWrt community, they just had good marketing. If your WRT1200AC device does not work well with OpenWrt do not complain to OpenWrt, but complain to the Linksys support.
The WRT1200AC family for example does not support WPA3, because the closed source Wifi firmware does not support it. The 15 years old WRT54G supports WPA3, it is just very slow. ;-)
Currently I would suggest the Linksys E8450 / Belkin RT3200 (same hardware) or some other device using the current Mediatek platform with MT7622 + MT7915 + MT7531. (2 X Cortex-A53, Wifi 6) All chips are supported in recent upstream Linux kernel, including Wifi. The Mediatek router team is currently doing pretty good upstream open source work for their chips.
I own an Omnia and despite it having been a bit rough a few years ago, it's now nearly flawless. The MOX is modular and could be more interesting for your use-case but it can also get pretty expensive.
It’s a lost cause. The router should be treated as hostile and shouldn’t be allowed to know anything if possible. DNS over HTTPS and that SNI encryption stuff should be used.
I have found that rather than finding a way to sneak ads in, most non browser apps will just detect that the ads are missing and throw up an error refusing to display the content.
My go to home router is the pcengines apu2. I run openbsd on them(not for security but because I really enjoy using openbsd), But just about any os will work well. They have opensource firmware.
Full disclosure, I have never built the firmware but I take great comfort that it is developed in an open source manner, and that I could build it if I wanted to.
One alternative could be, instead of buying a router, getting a single board computer designed to run whichever routing software you like. Banana pi is an example that comes to my mind. You'd need to get a case, and it won't be as neat as a commercial router.
I would love to replace these "routers" with a normal computer. The thing is these computers would need special ports for either phone lines or fiber optic connections, as well as built-in modems. I've never seen a computer with this sort of hardware built into it. Even on dedicated network cards I only ever see ethernet ports, nothing compatible with whatever it is my ISP is using (SFP?). Decades ago in the dial up days I used to be able to buy modems separately but not anymore, and I'm not even sure what sort of hardware components are needed for a fiber connection...
My ISP gives me a box that terminates the fiber and has ethernet on the other side. They also rent and sell routers that are configured to handle the pppoe and vlan settings needed for the WAN interface to this box. Plenty of routers can do this, and a dedicated Linux box like you are proposing should work, or you can throw a cheap managed switch in between if not. The hardest part is knowing what settings are needed (e.g. I had to call my ISP to ask for the pppoe password).
DSL standalone termination is still widely available, as are standalone DOCSIS cable modems.
If you're on DSL, the DLink DM200 has an integrated adsl/vdsl modem that's supported by OpenWRT, and the platform is quite powerful. You'll need a second device for wifi though but that suits my use case.
If you want a dedicated OpenWRT device Mikrotik would be my suggestion.
In the forums [0](Discourse alert) you have many threads with suggestions, too!
[0] https://forum.openwrt.org/c/hardware-questions-and-recommend...