Convoy S2+ with Biscotti and 7135×4 driver. Set it to mode group 8 and you’ll have your 300lm mode for sure. You can choose your emitter’s color temperature and TIR optic angle on purchase, just message Simon (the man behind Convoy) about it on AliExpress.
The only conceivable “problem” I see with your request is that it doesn’t have momentary on.