Ubiquiti isn't perfect but they make a really good product and you don't have to connect it with a cloud

Xfinity is absolutely collecting (and probably selling) data on the traffic of every device on your network.

They're doing that anyway via the modem. Unless you are tunnelling everything your ISP sees every byte you send.

I work for a different large ISP who provides modems and routers to our customers, but not this specific feature (being a bit vague because I know at one point mentioning the company’s name on social media would result in the post being reviewed by the social media team/referred to security for anything discussing internal processes, and while Lemmy probably isn’t on their radar I’d rather not risk it).

The amount of data we can see if you’re using our routers is pretty crazy, and most people have no idea. We can see exactly what you have on your network and what it’s doing. If you’re just using the modem and not the router, we have much more limited visibility. We don’t have the capacity to monitor everything everyone is doing all the time, so if you’re using your own equipment (and you’re not using our DNS service), it’s unlikely we have much data on your activity. Storage in the scale needed to store what everyone is doing gets expensive.

I’ve always used my own equipment, and I make sure everyone in my family has their own equipment as well. I would absolutely advise against using your ISP’s equipment if your goal is privacy.

Can you recommend some trustworthy hardware?

I know gl.inet is probably best for routers, but are any of the mainstream brands more trustworthy than others? TP-Link, Ubiquiti, etc.? I recently got a Zyxel, are those okay?