@baralong Here's what I did for an antenna: https://www.digikey.com/product-detail/en/pulselarsen-antennas/RO2408NF/553-2621-ND/3025771
That antenna would surely be in the deep deep overkill zone for physical size and cost, but it's nice for my application (wave height sensor on an in-water buoy). On the other hand, it's 8dBi gain is awesome for a "permanently" installed station.
The lesson here is go to digikey.com (or Mouse, Newark, etc., etc.) and begin searching for parts based on what YOU need.
Here is what I used to transition from the O2+ to the project enclosure bulkhead: https://www.taoglas.com/wp-content/uploads/2017/07/CAB.721-1.pdf.