Seal spoke nipples for tubeless
 

Has anyone tried to do that instead of using rim tape? Maybe using something similar to this:

https://adventuremotorcyclinghandboo...12/02/alpa.jpg

Motor bikers have been doing it (I know, lower pressures) but the thought I had is that on deep section rims, if the nipples could be sealed, one would have much more air volume. Even some shallower alloy rims would nearly double the air volume. This would make the pressure drop much less when you have a hole and the sealant is working, maybe add comfort.

It should work if you assume the rim is completely air tight outside of the nipples but that is not always the case.

HED Utilizes a neoprene nipple washer to help do that on some of their fatbike rims. Doing a wheel like that now. That rim allows it to then be sealed eliminating the use of tape.

So it's been done. Widespread - not yet. I am sure we will see more done this way.

Cool! Yes, many rims will have leaks, but that should be easy to fix. That may be the next wheel tech then, that everyone will "need" and will make us buy new wheels in a couple years!

I would not do it for the purpose you're thinking of. Should be fine on single-wall rims, but especially deep section rims are not designed to contain that much pressure inside the rim. At 100 psi, every inch of a 52mm rim the sidewalls would be subjected to 200 pounds of force trying to tear the rim apart at the seams, and that's in addition to the normal forces of cornering, bumps, etc.. Deep section carbon rim sidewalls would immediately bulge out, because they're thinner - just squeeze the walls of carbon aero rims to see how much they can flex with far less pressure.
Bad, dangerous idea on deep sections. Good idea on single-wall, but that wouldn't increase the air volume...
Bicycle rims are usually too thin to seal with an o-ring nipple like that page you linked.