My 2022 toy budget is in. How should I spend it?

To be honest and without sounding jealous, you seem to be quite lucky having a budget you "have" to spend on new gear, especially since you seem to be happy with your already pretty complete kit. To play the game however, here are just two suggestions:

1) You seem to be not completely satisfied with the Viltrox, you could either check out the Fujifilm 56 f1.2 or maybe go for a smaller, lighter alternative and have a look at the very good 50mm f2. Personally I am still eyeing the excellent 90 f2 which you once sold, however I can't justify spending this kind of money in the near future.

2) You seem to like the X-Pro line a lot, you also stated you enjoy taking just a single lens with you and you enjoy the 35mm equiv. focal length a lot. I might just throw in the X100V here: It essentially is a mini X-Pro3 with an excellent 23mm f2 lens. It is compact, fairly light, shares a lot of functionality with the X-Pro3 and has a few unique features on it's own, like the leaf shutter or a built-in ND filter for shooting wide open in the sun. It's also much more convenient to carry around than the rather chunky X-Pro3. I too own the XP3 along with a trio of Fujicrons, however I find myself using the X100V more frequently and especially: I often take it with me when I wouldn't bother packing a camera at all.

Other than that, I agree with Nurse Marty. If you really have to burn the cash and already own gear you are mostly happy with, why not spend the money to not only gather new experiences but return home with unique shots, newly gained knowledge and maybe inspiration for future outings? I think all of that is worth a lot more compared to a new lens which does somewhat better on an MFT chart.