Chinese radio users know well, that grid power is needed to charge their radios. The reason is that their charging is tied on the 110/220V power and the radios’ own cradle charger.
To eliminate the charger it is impossible, but to replace the power to the charger is possible.
The Baofeng UV-5R and siblings’ charger demands 10V and there are various ways to replicate that.
The latter is one such build.