Does any known anywhere that stock roval rim plugs (that fill up the holes for the spokes)?

Not sure but I would try specialized concept stores or sigma sports.
I used them for about two years with no issues but decided to change to rim tape because if you ever do need to put a tube in, roval say that the plugs could puncture the tube ( not that I ever did need to put a tube in!)

I asked this at my LBS last year and got told they werent available anymore, I really get on with the 2bliss rim strips for tubeless so wasnt a biggy for me.

2bliss strips are dead easy to use

They do still make them. Not sure if you can buy through a shop but occasionally come up on ebay. Got to be careful though, there’s more than one version. The road version doesn’t work with mountain bike rims. The mountain type may not work with different rims. Depends on the shape and thickness of the rim bed for proper fit and seal.

Would veloplugs work instead? I used these on a weight weenie build years ago and they were fine. Still available by the looks of things.

Some where in the Aladdin’s cave at the back of the garage I have the unopened bags that came with the Roval Traverse SLs.
Couldn’t see the point of them as the wheels had 2bliss strips which are first class