Yes. Had them since WHF first started. We have different rules depending on the level of the meeting though.

40-50% of the meetings are low risk and they don't require removal or power off and these devices though.

For medium risk or higher we run random tests during meetings to see if they have google and alexa around. Nothing fancy or anyting. We just have they devices play a song like "Never Gonna Give You Up".

Yes - in fact some firms are recommending they be disabled altogether near work areas, including at home.

We configured endpoint detection tools (ie Very Popular Endpoint Product) to scan local networks for these devices based on open ports and mac addresses. It is fairly straightforward to fingerprint them. Not foolproof (wifi isolation and other network segmentation), but low hanging fruit.