Honeywell has a line of simple pressure switches. I think they are all NPT, so youd need a NPT to BSPT adapter. Youll have to play around for a few minutes with a multimeter to determine if you need a N.O. or N.C. switch. The plug would need to be changed as well.
https://www.mouser.com/datasheet/2/1...et-1627427.pdf