Suggestions for installing video doorbell without existing doorbell.

Well if you got an electrician out he would have to wire it for very low voltage for it. I cant remember what the voltage is but its low as i hooked mine up without turning off the power and touched the wires and nothing happened so you could try that. Im sure and electrician knows what the voltage is to a doorbell and how to do it.

I don't know if this will help or not, but I had an older home without a door bell but didn't want to put in a transformer. I found this adapter on Amazon that solved my problem and works great! https://www.amazon.com/dp/B07T3GBX1L?ref=ppx_pop_mob_ap_share.

Good luck!