If your batteries voltage doesn’t match the voltage of your LED you need a voltage regulator anyway. All you need is to design it in such a way that it will always provide something close to the right voltage (at the expense of run time when fewer batteries are available).
IIRC the Logitech wireless mice work that way too. They can take one or two batteries. Use two for long life or only one if you prefer a lighter mouse.
If your batteries voltage doesn’t match the voltage of your LED you need a voltage regulator anyway. All you need is to design it in such a way that it will always provide something close to the right voltage (at the expense of run time when fewer batteries are available).
IIRC the Logitech wireless mice work that way too. They can take one or two batteries. Use two for long life or only one if you prefer a lighter mouse.