There's already a thriving market in muted airtags, a quick ebay search will get you there.
There would be the hazard that you can no longer say it was an accidental stalking if you use a professionally tampered with device. Given that there are a lot of iPhones out there even if your device doesn’t detect it your friend may ask what is up. Then law enforcement can use the AirTag serial number to track back to the account it is linked to.
Yep. But there is also potential for civil disobedience / mischief there.