Use two. I normally combine a large, steady (AAA powered) red light on the rear rack coupled with a USB rechargeable Lezyne Strip Drive set to L-R (think Knight Rider!) which is clamped to either seatpost or luggage depending where most visible.
The Strip Drive has performed faultlessly over 5 years now, think it was about £30. Good investment IME. It has a simple charge indicator which is also useful, and doesn’t require a charging cable, it has it’s own USB connector. Not sure if newer versions do or not.
The steady light on the rack is a Trelock that I borrowed from my Dutch bike. It has 1. A large integrated reflector and also 2. Side visibility. Two points often overlooked. Certainly by me (before I learned to drive)
There seems to be a gadgety trend in the UK for micro-sized lights with little to no integrated reflector 🤦🏼♂️