Update on Lockdown Mode:
1. I’ve barely noticed anything on macOS or iPadOS. Web browsing is slightly impacted on the iPad, but that’s not a huge deal. It’s basically invisible on the Mac. Connecting accessories requires an extra confirmation, but that’s about it.
2. Things are more complex on the iPhone. Focus modes aren’t shared, including Sleep mode for Do Not Disturb functionality. The indexing of images and text in message history is disabled, so finding anything via search is almost impossible. Web browsing is much more noticeably impacted here, with some website icons and images being replaced with random emoji. A lot of very small things are broken.
Verdict: I’ll keep it enabled on the Mac and the iPad, but I may disable it on my iPhone. Either that, or I’ll leave it enabled and disable it temporarily as needed.