I'm surprised noone has responded to your question yet, so I'll take a stab.
If I understand correctly you want alexa to announce if someone presses the doorbell, and you want to use the yolink app.
If you have an existing doorbell, I see two possibilities. If you want to keep the chime, an automotive relay could be wired in with the chime/doorbell transformer and used to trigger a hacked yolink contact sensor, or if you don't want the chime you could simply wire the hacked yolink contact sensor with the doorbell wires.
With that said, for the price of a yolink contact sensor and a relay, you could come pretty close to the cost of a ~$35 video doorbell that "works with Alexa".