Update--and end of thread? Bought the lights from Arsenal, and again, I have no connection to Thomas ___? except a riding partner who know him somewhat. The lights are nicely compact, water resistant, and come with a single USB charging cord that connects to all four (one headlight and three taillights: helmet, seat post, and seat stay). They're easy to program, and hold a charge (supposedly) up to 20 hours, depending on the blinking you choose. "Thomas" included a hand-written note that they were already charged for about a four hour ride--as if I were so covid-containment crazy that I needed to get out with them before charging them. (Not a stretch, really.)

Anyway, I won't include a link lest anybody mistake me for a stooge here, but they're easy to find. For four lights so well-designed, they don't seem too expensive to me compared to other options. Taking them out for a second spin today.

Thanks for y'all's thoughts on this.