Jalaneti (jala is water in Sanskrit, so water neti[1], it is a yoga practice) may help with sinus and other nasal congestion problems. It seems to, for me, anecdotally.
Standard disclaimer: not a doctor.
But I have been doing jalaneti for years, since my teens. First learned about it from a course at the Yoga Institute[2] of Santa Cruz, Mumbai, India.
After jalaneti the nasal passages feel very clean for sometime, and breathing is more free. You can do it once or twice a day. Used with caution, it is not dangerous for healthy adults.
[1] https://en.m.wikipedia.org/wiki/Neti_(Hatha_Yoga) You can ignore the clairvoyance claim.