I’m an ultralighter and EDC a 4oz/5W $30 set-up that’s the equivalent output of my iPhone wall charger, and provides ~4hr screen-on runtime per 1hr of stationary cloudless sunlight. Could be doubled-up/daisy-chained for a 10W set-up plus a $20 10k mah powerbank for ~1 lb - that should be plenty for most folks. These include a USB multimeter so you know what works, and how much power is moving.
FWIW, I tend to find solar only worthwhile when charging from an outdoor stationary position on a cloudless day (eg. during lunch) you suffer a lot of inefficiencies riding through shadowing, from passing clouds, imperfect angles to sun, etc.