A hot water tap, yes, everyone's got one. Actual hot water coming out of it immediately, less likely. My bathroom faucet takes a good 25 seconds to get to maxim

A hot water tap, yes, everyone's got one. Actual hot water coming out of it immediately, less likely. My bathroom faucet takes a good 25 seconds to get to maximum hot, mostly from distance (WH is in the garage) and partly from being a low flow faucet. A bidet has a very small flow rate, so for my situation, a self-heated reservoir is the only way to get immediate warm water.