If it’s $200 in parts then a premade item would be at least $400 and probably $500. There probably isn’t much of a market at those prices.

The bill of materials needs to come way down to sell it for much less than that. Buying the parts in hobbyist-level bulk (100 pcs) probably would only shave $100 from the final price.

https://www.lilygo.cc/products/t-encoder-plus looks like the HW part is taken care of, and they have some sample code on github