@pganssle Hello Paul, good evening and welcome to Qoto.
Seems no one replied to you and gave you the welcome we try to post to all new users; until now, that it is.
I wouldn't consider that you are worrying too much - taking a risk when it's not essential is not a good thing, there are a lot of bad actors out there, including state agents. Lock it down and keep it private is the best, imo.
I wouldn't think it's an exaggeration or an undue scare. I had a linux firewall for years on my home network, before the commercial routers started to become any good and secure.
I used SmoothWall, running on a spare older computer, and it had a lot of nice features and controls.
Have been using commercial routers for the past few years, most of the time with custom firmware - Tomato is the one I use.
Enjoy your stay, post any topics you are interested in for discussion. Reminds me I should go and take a look how the Smoothwall project is doing nowadays! 😄