TBH I shot (and still do to an extent) Olympus Micro Four thirds for years, and never thought I'd swap, but over recent years, I've found myself transitioning from Olympus to my Nikon Z or Sony A7xx system. It's not that Micro Four thirds is bad (it most certainly isn't) and I still love the system overall, it's just that I think a lot of what made M4/3 great (body size, features, IBIS etc), have now been matched or bettered in some cases by full frame (the latest Sony A7xxx cameras despite being FF are still about the size of an Olympus OM-1 body). Lenses to an extent still can make a difference to the package weight, but my superb Olympus 300mm F4 (600mm FOV FF equivalent), is now matched both optically and size / weight wise) by lenses like the brilliant Nikon Z 400mm F4.5, which when shooting in APS-C mode on my Z8 or Z9 also gives me a 600mm FF FOV.
I think computational photography is where perhaps Olympus / OM-Systems still maybe has an advantage, but that's being eroded with each generation of FF camera. Also the pretty much limited lack of development in M4/3 is a little worrying (OM-3 aside which still uses the same image sensor as the original OM-1).
