I spent way too much time obsessing over primes when I first got my M10. Honestly, I started with a pancake zoom and it really changed how I shot because I wasnt constantly worrying about being too close or too far. I eventually picked up the Olympus M.Zuiko Digital 14-42mm f/3.5-5.6 EZ and it is crazy how small it makes the camera. You can literally fit the whole setup in a jacket pocket which is huge for not looking like a photographer in public. But if you want that prime quality, I actually prefer the Olympus M.Zuiko Digital ED 25mm f/1.8 over the wider options. It gives you a 50mm equivalent view which feels way more natural for framing people from across the street. The AF is lightning fast too. If you can find a used Olympus M.Zuiko Digital ED 12-45mm f/4.0 PRO, it is slightly bigger but the sharpness is next level for street work.

Just catching up on this thread... quick question tho, do you prefer getting right in the action or do you like keeping a bit of distance? If you want a versatile middle ground, I totally recommend the Olympus M.Zuiko Digital 25mm f/1.8. Its super tiny, lightning fast, and usually cheaper than the 17mm. Tbh its often sharper too, making it a great budget-friendly street powerhouse.

Honestly, if you're starting out with that E-M10 IV, you basically can't go wrong with the Olympus M.Zuiko Digital 17mm f/1.8. I've used it for years and it's really the perfect balance of size and performance. On M4/3, that 17mm focal length gives you a 34mm equivalent, which is just wide enough to capture a whole scene but tight enough that you aren't getting weird distortion on people's faces. It's super snappy with autofocus too, which is basically a requirement when things are moving fast in a crowd. Another reason I always suggest this one is the manual focus clutch. You just pull the ring back to show the distance scale. This is a game changer for street photography because you can zone focus. Basically, you set your aperture to f/5.6 or f/8, set the focus distance to 2 or 3 meters, and then you don't even have to wait for the AF to hunt. You just click and the shot is instant. If you're really worried about the footprint, the Panasonic Lumix G 14mm f/2.5 II ASPH is a true pancake lens that makes your setup tiny. It's super wide tho, so you gotta be brave and get close. Honestly, the 17mm is the sweet spot. I'd skip the Olympus M.Zuiko Digital 45mm f/1.8 for now unless you specifically want portraits from further away, since it's a bit too tight for general street stuff imo. The 17mm is the best bang for your buck by far.

My buddy told me the exact same thing last week. Guess he was right lol.