If your friend isn’t a flashaholic or simply doesn’t want to deal with separate chargers why don’t you recommend one of those 18650s with a built in micro usb charge port. (Although idk if they will fit in the S2+ configuration you have)
Supposedly its about $14 w/ coupon code DSX2GTUB on amazon right now. https://budgetlightforum.com/t/-/42205