Mh, I must admit that list was harder to fill than I thought when I wrote above comment. Afaik, Muun, LND, Munstr, and BitGo use MuSig in production although some of them are still experimental. At least Nunchuk, Bitkey, and Liana are working on MuSig support, I would imagine a number of other hardware and software wallets are also at least looking at it.