I’m quite sure late to this, but I found the Heiman C1-M is a Carbon Monoxide detector that supports Matter, Thread, and Zigbee by using a Silicon Labs EFR32MG24 chip, and has Intertek ETL certification per UL 2034. Amazon has the C1-W model which isn’t Matter unfortunately.
Alibaba does have it, but I’d have to buy in bulk even though I only need 1.
I’m considering buying their minimum quantity, then selling the extras on eBay or wherever. Do you think you might buy one if I did that? Or a few? Just trying to gauge interest. I know I’m super interested, but unsure of others.