Hmm is 3.2V close enough to 3V?
I wonder if a solar light could be hacked as a solar power manager and power source?
https://www.bunnings.com.au/solar-magic-lithium-14500-3-2v-rechargeable-battery-2-pack_p4351891
There are variopus dirt cheap versions available in oz.
https://www.bunnings.com.au/click-solar-led-garden-light_p4351452
Crush or desolder the LEDs?
Edit: I had a closer look at my local hardware shop (Bunnings). There were only a couple that were 3.2V. They tend to be the higher lumen, higher cost ones (so not so tempting to tinker). Most of the cheap ones are 1.2V. Quite a few use 3.7V (especially in the higher lumen range).