Are there pancake lenses for the A7C? While in Japan I saw a lot of older japanese guys with some camera which I couldn't identify, it looked like some digital remake of some older camera, but what struck me was that they all had this pancake lens which made the whole package very thin and small.
My A7C is also very compact already but the 35mm 1.8 lens is, while very compact, by far not flat, so I can't put it in my pocket for example.
It doesn't need to be very fast, because I will use it mostly outside in good light.
Regarding “digital remake of some older camera”: there are a lot of APS-C and MFT cameras that resemble older cameras, like the Nikon Zfc, which will have smaller lenses because of the smaller sensors. A good example is Sonys 20mm F2.8 which is super small but only APS-C compatible.
I had the Sony Zeiss 35mm f2.8 and for FF I think it was pretty compact. You could also look into manual lenses, for example the 50mm f2 from TTArtisan is very small and affordable.