Oh whoa... You remove your panniers and walk around with them? Yeah, that's got to be a major PITA. Is there no way to secure them to your bike to deter theft? I have set of canvas panniers from Roswheel that I wrap a chain around and through effectively lashing it to Frtiz if I feel like it's a high traffic area. Either they'll have to break the lock or slash the pannier straps rendering them useless.

I also usually carry a string back pack (stuffed in a side pocket) to carry small items around that I don't want to leave unattended.

Be that as it may, there are quite a few of them around here. My main way to access points south and north takes me across downtown on 4th street and there are many that zip around with those hot packs on their backs who work for Favor. If I were to do it (and I'm not) I'd try to plan to pick up the orders in the same general area to increase efficiency. I don't know if it's worth it, but there are a lot of people around here who do it.

Bike theft is still bad here in NYC even though crime overall is way down. I don't want anything to be removable even by slashing.

Dang! Freaking animals! Leave my bike ALONE, JERKS!

Probably because nobody ever seriously considers a bicycle to be a transportation vehicle.

Cargo bikes have a front trunk compartment. I wonder if any of those have a locking lid.

use the bike to ace traffic. it worked for me, really

I have a pair of Ortliebs and the strap that is used to close them can also be used as a shoulder strap. That works really well. They are still a bit cumbersome to carry but much easier to carry as shoulder bag.

My Ortlieb panniers don't have that option.

Just get a proper rucksack. When camping in Germany, I found it easy to ride with a 60l rucksack. This was MTB rather than BMX.

Also, get some real bread rather that can't be crushed rather than that fluffy, sugary, presliced stuff you guys stateside refer to as bread

Also, those Ortliebs that double as a backpack are very uncomfortable.