I’m looking for a Thread button or rotary encoder to control my smart lights, preferable under $15. It can be battery powered or wired. I have a border router across the house, within wifi range. Does anyone have any recommendations?

Sounds like a good fit for ESPHome.

Not Matter but this one looks interesting : https://blog.prusa3d.com/a-cheap-smart-light-controller-thanks-to-3d-printing_136243/

The only one that I'm aware of is the new BILRESA from Ikea. It's $9.99, so not much of a risk to try it out.

I use this - IKEA Bilresa scroll wheel. It also comes in a 3 pack for $28.

I’ve got it working in HomeAssistant, and they’re pretty neat. The knob has a click action, and the remote has a click action, too. Clicks on the remote allow you to select between 3 different ‘channels.’
In HA, you can set each channel so that the click and scroll does something different. (The blueprint I use has click, long press, double, triple, and quad click, as well as scroll wheel actions.)
I’m not that fancy - I’ve got each channel’s click action mapped to on/off toggle, and to brightness, color temp, and a hue scroller.

Nice.

Would this work well as a volume controller?

We've got a complex setup and when guests come, they need something simple I can throw at them...

This uses Matter, not thread.

This is just a WiFi device using matter protocol

(It has very mixed reviews also)

Nah.

While they do use the Matter communication standard, these devices use the Thread protocol.
The Venn diagram/conceptual model of how these interrelate is messy because Matter can run on both Thread or WiFi (depending on the hardware of the device), and Thread is a platform that supports multiple standards.

These remotes are Matter over Thread:

I do have access to a 3d printer so I think ESPHome is the answer

I think I’ll try the IKEA thing that was mentioned in other comments, and maybe I’ll make something with ESPHome if I need something else.

I really want to try some of their stuff but it’s always sold out at the EPA store. I keep meaning to make a pilgrimage up to Emeryville but I have a suspicion it’s going to be the same. Plus I’d just rather visit friends if I go all the way to the east bay.

I think I just need to get out more 😌

Oh good to know!

At least on my regional product page they don't say Thread anywhere in the whole page.

I think I only knew that before I bought because I watched a review over them. I’m on the same page regarding IoT devices on WiFi. Needs must if I have to, but I keep a separate WiFi network for them, with different access rules.

On a review of the blueprint I’m using in HA, it does appear so!