I am super sensitive to over engineering. For my doorbell I wanted something that lets me play a custom bell sound. You would be surprised that 99% of the solutions out there are complete over engineered stacks that depend on wifi devices, Internet access, connecting to various cloud services... So I built my own: a basic wireless button sends a radio 433 MHz signal, and my receiver is plugged inside the house and triggers an off-the-shelf playback PCB module that reads an MP3 off an SD card and plays it on a speaker wired to the module. No Wifi, no Internet, no cloud, no apps. And the rare times I want to change the sound, I update the MP3 on the SD card.

Edit: there are very, very few products on the market designed as simply as this, just an R/F signal triggering local playback. I think the only commercial doorbells designed like this I found were an out-of-stock product, and a UK device designed for 230V that would have required a bulky adapter to work for me in the US.