No, this is May version. If you look at the twitter thread, the October version is different and looks much more "stock"

(sadly I have not found nice website with newer version photos yet)

I heard they reduced the battery size to make space for their chip.

This one too (pardon the AI slop): https://www.tibane.net/research/ledger-nano-x-implant

Is that safe for devices containing a lithium battery?

They could x-ray it, carve out epoxy with nothing inside, put the logger, apply epoxy.

Take off the case, put your own entire module in, put the case back in. Epoxy doesn't solve much.

...frankly, selling one as DIY kit have highest chance for tamper resistance. Tho pretty untenable with small SMD components sadly