Citrus often have graft compatibility issues, despite being in the same genus, but if you can’t find the specific cultivar/rootstock combination listed in graft compatibility charts, you’ll just have to try a few to see what works for you. Lemons and kumquats seem to especially have unexpected incompatibilities sometimes.
Have you tried the search feature on here? Because some people have already compiled that information from time to time, such as this:
And as far as air layering, this thread includes a few different people’s techniques with photos: