Wellp, those “solar lights” you plant in the ground, used to take 1/more NiCd/NiMH cells, and a step-up converter. Now, lots of them just take a nice simple LFP cell and small resistor.
Ie, you’re running those dinky little LEDs at maybe 20mA, not 1A/2A/5A or more, so the Vf will be quite a bit lower.