If you can’t see a pedestrian on a shared use path then you either have the angle wrong, or you are travelling too fast for the conditions, both of which may be due to over reliance on 1500 lumen floodlight style MTB lights.
Being a proper fussy git I’ve got the angle right for road use, and I noticed recently (this winter being the first year I’ve ridden shared paths because I’m doing some of the school runs) that pedestrians in dark clothes just aren’t realistically visible until about 20ft away, which is maybe a second and a half at the speed of the 7 year old I was riding with. If you’re in a dip in the path the distance is shorter still.
I came to the conclusion that yes, we should slow down a bit, but safe shared path riding with a German beam does mean jogging pace at best. Which isn’t ideal.
(And FWIW the most powerful MTB light I’ve ever used is a 400 lumen Joystick.)
+1 for Rose. Starbike and Bike24 sometimes have some good deals, too.