Would you consider used? The EM5 Mark II is an excellent camera and has great weather sealing, just be aware though that for a camera to be weather sealed the lens needs to be weather sealed as well.
Fuji uses and X-Trans processor rather than the conventional bayer sensor and as a result different softwares have had difficulty demosaicing the files. Lightroom used to be shocking, giving a very watercolour or painterly effect especially with landscapes, but it is much better now with the later versions and especially CC. Processing does still require a slightly different approach to sharpening but you can get very good results now, with VERY few images being affected to the point it's not worth worrying about imo. I still find some of the jpegs can have a hint of this effect, but that's a very decisive opinion and again 99% of the time not an issue. Fuji images are very pleasing and they have quite a fan base over their colours. I mention it only so that you know you need to apply a different approach
The smaller the sensor the worse it will be in low light, that's just physics, however my experience with Olympus was very positive. Their IBIS is class leading and I've managed to handhold shots at 24mm eq for 1s allowing me to keep ISO down. Of course, if shooting on a tripod noise handling becomes less of an issue as well, and Olympus (maybe Panasonic too) have. vey clever noise cancellation feature with long exposures (I think those 1s and over) where it takes a second blank shot and then uses this to remove the noise from the first image, creating a much cleaner raw file. Also, the EM5-II has better low light performance than the G80 despite the same size sensor, the EM5-II scores 896 on DXO vs 656 for the G80.