Thinking of downsizing from FF - Options for similar setup? Advice?

I've been shooting with my Sony A7IV (as a hobbyist) for a little over a year after replacing my 6D MK II. My original reason for upgrading was due to size and weight and now I'm thinking of the same issues again, this time I'm thinking that it may be a case of moving down the sensor sizes to either APS-C and M4/3.

I know the majority of the size/weight savings from a smaller system actually comes from the lenses themselves, so here are my main focal lengths uses at the moment:

My main concerns about moving down the sensor sizes are:

• Depth of field - I know there will be less DoF rendered when comparing the same aperture. I do like to shoot the odd portrait here and there, where a nice soft bokeh is apprecited.
• ISO performance - I know a larger sensor gives more area for light to gather and therefore has better low light performance in terms of not needing as high ISO as might be required by a smaller sensor.

Literally any info and anecdoted about moving down in sensor size would be much appreciated.

I should say that I actually started with M4/3 on the Lumix G1 before moving to APS-C with the Canon 550D (T2i) then to the FF 6DII, so I'm not unfamilliar with these systems, but it has been a very long time since I used them and didn't particularly have any high end glass for the smalller systems due to my age at those times.