You know what's weird? I get severe sinus headaches and regular pseudoenepherine sudafed doesn't help at all, but these phelylephrine ones do. I'll even tell my wife "the little reds, not the whites". Weird.
Have you tried a migraine formulation for that? It sounds like you're actually benefiting from the systemic effects (vasoconstriction) instead of the reduced mucous production. A formulation would include caffeine that also has vasoconstriction in case this is removed from the market.
When I had COVID and got really severe congestion, it was some of the worst sinus pain I've ever had in my life. I was at the point where I was trying to use a baby nasal bulb to relieve some pressure. The phenylephrine helped me a lot more than any other medication I was trying, including nasal sprays. I also take other sinus medications though, so I wonder if it's a case of a medication not working well unless it's used in conjunction with other things?
I guess it's possible I experienced a placebo effect, but it seems weird it would do it when nothing else was.