I've been doing a fair amount of research on this subject lately in hopes of assisting an elderly foreign neighbor who is seeking a solution for sleeping, and mild chronic pain. I've been looking ideally for a THC:CBN orally administered product.
I do not think there is a reliable gummy solution. And most (not all) are imported, so quite expensive.
There are locally produced gummies (and other edibles), but those are mostly THC and/or CBD.
There are a fair amount of imported brands, which are legitimate. But the mark-up is 2X - 4X (from Canada or the U.S.).
There are a lot of fake product, mocked up to imitate imported brands.
There are a boatload of oils (oral) but it is challenging to get details on the exact make-up of these. Most are CBD, which may be more "legal".
There was a lot of promotional activity (on line, Facebook) surrounding last week's 20th National Herbs Expo (Thailand Herbal Expo 2023) and the 20th National Technical Conference on Thai Traditional Medicine, Folk Medicine, and Alternative Medicine . And I didn't see anything interesting.
Things might change in the future as many plan to pivot to "medical" if flower gets relisted as a narcotic. But the medical market would require additional legislation, or proclamation, to expand beyond its very limited use today.
Search on Facebook (LINE, Twitter, IG) for cannabis/THC Gummies and very shortly the algorithm will start serving up dozens of "options". Follow Cannabis shops on LINE, where some offer edibles.
I think that there is a wide selection of legal cannabis flower here in price ranges from a few baht per gram upwards. There is a long thread here on that. Comparing prices, product, etc. with other markets is an interesting exercise I guess, but ultimately of little use, other than to complain about.