GM-5 is probably the greatest pocket-size mirrorless, and maybe the last. The GX-85 is also great, but it does have a larger grip and more of a shoulder at the top.
The G-100D is also quite small, but the faux pentaprism at the top makes it just a bit too big to justify being MFT.
https://petapixel.com/2025/06/28/the-panasonic-lumix-gm-5-is...