I have a Triumph mesh/textile jacket that has armour and a back protector. Got it from World of Triumph who always have Triumph branded clothing really cheap. Think I paid about £30? Is actually a decent casual jacket too. Seems like it’d hold up pretty well in a crash. I’ve had a lot of Triumph branded clothing and it’s good quality – rebadged Alpinestars etc.
I used to wear that with a cycling baselayer on under, kevlar jeans and some puma ankle boots and full face helmet.
Worked pretty well, but only when you’re moving. Stopped at lights gets you cooking, especially with the motor and exhaust heat. I think that is kind of inevitable though.
Ex-wife had a full set of Hein Gericke summer mesh textiles which were crash tested (40mph lowside) and stood up to it fine.