I have been tempted to contact Tooltech Gunsight. They can drill sights and install tritium inserts. Way before night sights were available for the HK45 and HK45c, people sent the slides off to have this done.
They do Beretta 92 front sights this way. I know someone online who had the PX4sc done this way too. Those sights were somewhat small, and they managed to pull it off. I think the sights for the shield should work this way too... If regular, plain white circles trijicon night sights don't come out soon, I may give it a go on one of my Shields