Our best bet for a sailfish connected smartwatch is indeed AsteroidOS.

Kido and others made attempts to build an sfos client called Starfish.
It was in planning to release with 1.0 last Q2 but got skipped due to a nasty bluetooth LE bug (or sfos shortcoming?) regarding authentication.
Jolla is aware of the problem but last news from them are from pre summer.

So literally we (all) are waiting for jolla to give any new feedback to this bug or solve it, to have someone else do a Sailfish Sibling Watch for them (they could again build upon) including client. But even that ... is ... slow... currently and gives a hint on how high watches are on Jolla-priority-list.
My bet, someone else finds a solution before Jolla does