Documentation of a Covid booster shot for travel

I'm eligible for a booster shot in the US. Currently documentation here is a mess: You get the CDC health card, which anyone can photoshop in 20 minutes. Most of the documentation is done by the providers: My provider issued a PDF certificate and and a digital smart health card (which very few apps can read) and I managed to get mine transcribed into a EU certificate as well. My original provider doesn't offer booster shots, so I need to go to a different one: they will not be able to combine my records.

Chances are that booster shots will soon be required for travel as well. Given the flood of fake vaccination records in both the US and Europe we'll probably see a tightening on security requirements and a simple hand written card seems to be the absolute worst in terms of security

There has been talk about international travel or vaccination passes that would make life for airlines and passengers a lot easier. Are there any of these already in existence? Are there any expected to come online soon and does any of these have potentially provisions for documenting boosters as well?

Any other tips or tricks how to handle this efficiently would be appreciate: main goal is ease of use, wide acceptance and reliability. I don't care about privacy.