I have seen some people use Christmas lights. I had a 20ft led string on mine for the last santa ruck. Charged solar.

You could also use the headlamp below. I recommend pointing it down at your feet by either, attaching it to the bottom handle of your ruck or hang from the bottom molle. It is by far the brightest head lamp I have had and bought 4 after Cadre Fagan lit up a Forrest with his.

https://www.amazon.com/dp/B07GT49F9C/ref=cm_sw_r_cp_apa_i_b11LFbC2BQTJC?_encoding=UTF8&psc=1