It’s actually quite safe to use Bluetooth keyboards.
Since 2009 on, bluetooth keyboards have encrypted all traffic end to end with the exception of service discovery. In other words, only the advertising packets that basically say “I’m a keyboard” or “I’m a trackpad or mouse” are unencrypted. Everything else, including the authentication is encrypted.
This has been discussed on other SE site. Here's the link for the same:
The gist being, Bluetooth connection is encrypted, hence safe, and the computer makes you enter a code on the keyboard during the pairing process is done to protect. So this guards against the man-in-the-middle attack.
Encrypted connection between ...
It turns out Bluetooth Explorer has an awkward UI, whether by sloppy design, implementation, or bug. The HCI Controller Selector does not show the active controller in the menu. It shows you the first item of some default menu order, even after you've picked a different item and clicked Activate. But the different controller was activated, even though it ...
You can connect multiple bluetooth devices at one time to any device that supports bluetooth.
There's nothing special about the iPad bluetooth setup. I have a few iPads and I connect Apple Pencils and bluetooth speakers and a Brydge keyboard to them at the same time.
To address your edit to your question, you can't use more than one device of the same ...
Technically, those adapters don't exist.
The USB device should be recognized by the Mac OS not as another Bluetooth device, but as an Audio Device.
I agree with you on this one. You definitely don't want to have a secondary Bluetooth adapter appearing in macOS. So to clearly define what you're looking for is a USB audio interface with Bluetooth ...
I’ve been living with this annoying issue for a year or so now and I am delighted to say it appears the most recent iOS update, version 13.5.1, has fixed this issue!
I no longer see AppleTV as an option when toggling speakerphone. It simply puts the caller on speakerphone.
No, you can't direct Siri to a different output than the default output.
If your iPhone is connected via bluetooth to your car stereo then that's where sounds will be directed.
Your options are to disconnect bluetooth from your car stereo or upgrade to a CarPlay-enabled head unit.