Talk to them like a four year old and say its rude to interrupt you need to wait your turn?

Make an office talking stick thing. When they interrupt the person holding the stick gets to shake it at them, something tambourine-esque.

Start interruption tipping, where everyone goes into a draw for how far into the meeting until this person will interrupt, when the condition goes off, everyone slaps $5 on the table and says who won. Danny had three minutes, everyone hands Danny a fiver.

Move to zoom meetings and mute them.

Sponsor everyone in the office to learn sign language except them.