Damus will do this eventually. First via remote control of wallet nodes and eventually a breez-style non custodial wallet but this is much further down the line. Zapping on damus is pretty frictionless atm but could be better.
Discussion
In this situation is there still space for no sat shaka reactions? May be a bit redundant to have frictionless zaps and reactions
I assume you would preset how much you want to tip, and zero is one of those choices.
Their could be two buttons, one with a preset amount, and the other with a slider to easily change the amount.