If you want something that is compatible with your Olympus in terms of color tonality and menu structure, consider looking for a used Olympus Stylus-1. It has an equivalent 28-300mm range (same range as the 14-150mm Olympus lens). The Stylus-1 has a f/2.8 constant lens, but the camera when it is turned off fits in a jacket pocket. It uses the BLS-5/50 battery used by most of the Pens and E-m10 cameras. It was introduced in 2014, but after a year or so, it was discontinued.
If you want weather sealing, I have a Panasonic FZ300 (25-600mm equivalent lens). It is fairly big (my E-m5 mark I + 14-150mm combo was about the same size). I have shot with it in wet weather. It is similar to my other Panasonic cameras (G85, LX10) in that you need to dial in exposure compensation to avoid burning out the highlights and the high ISO JPG noise handling goes to watercolor mode more quickly than Olympus cameras do.
My preferred solution has been to go with the Olympus superzoom lenses (first 14-150mm mark I, then 14-150mm mark II, and now 12-200mm). I pair it with my f/2.8 zooms (Olympus 12-40mm and Panasonic 35-100mm mark I), using the f/2.8 zooms in lower light situations, and the superzooms in better light when I prefer not to switch lenses. Since I keep the old bodies as I upgrade, I often go with two bodies, one with the 12-40mm and the other with the current superzoom.
With the 14-150mm mark II, I have shot in a number of wet environments, including taking it on the boat ride at Niagara Falls where you get drenched for about 10 minutes. Since I got the 12-200mm, I haven't done much shooting due to covid.