Nichia is pretty top of mind for me as a solid supplier of 265-280 nm LEDs https://led-ld.nichia.co.jp/en/product/uv_top.html. Decently high output, decent lifetime (especially the longer wavelengths). There's also CrystalIS https://www.cisuvc.com/klaran-for-disinfection/ But there's tons

This review paper is from 2019, but it includes a good summary of basically everyone who's relevant to the field https://www.nature.com/articles/s41566-019-0359-9 The author used to keep an updated figure on his website but sadly it seems to be down, or have moved

SilannaUV has 230nm, 235nm and 250nm wavelengths, as far as I know the only supplier that does so https://silannauv.com/

I would be pretty careful with all of these wavelengths though. None of them are truly monochromatic far-UV. Use eye/skin protection when messing with them.