Are there any official merch of utauloids? (other than the teto nendoroid)

Almost every UTAU is an independently created original character. Some artists sell small merch like stickers and keychains of their own UTAU characters. These can also be considered official merch, because they're designed and sold by the same artist who created the character.

As far as big game goes, only ones I know of is Teto with the nendo and the yoshiwara lament one.
It is at the discordian said, that people who make small merch of their own characters can be counted "official" in technicality.
As far as unofficial ones, there are some defoko figurines that were sold at some events throughout history. I tried searching for Momo but there wasn't much to be found.
Getting the rights to produce those two are... Difficult, since their creators have just about dissapeared.
Produce your own merch :DDDDDDDDDDDDDDDDDDDDDDDDDDD

A good place to look for UTAU merch is Pixiv Booth, since that's what most (at least in the Japanese community) use for creating/producing their merch.