I have an Astronomik UHC-S filter which passes only Hbeta / OIII (greenish blue) and Halpha (red). This is suitable for nebulas, but will also work for broadband objects like galaxies and clusters.
Available in AU from
https://www.bintel.com.au/product/as...k-uhc-filters/
Even under LEDpollution it blocks something as white LEDs have a strong dip in OIII
/ Hbeta and Halpha light output.