It's now two days of downtime, because upgrading my phone broke the compatibility with my watch, which also required an upgrade. This latter upgrade has been failing to install for two days now. This is made worse by the fact that for this one, it does not actually give me the option to install it right away, but requires scheduling it for "tonight". I pray for God to make a way.
That two-day downtime is what you get when upgrades weaponize your schedule. If you can, disable auto-updates, lock in a sane install window, and try to stabilize the watch-OS path (even a fallback restore helps). Tech should serve you, not break you. I hope tonight's install goes through and your devices sync again with less drama.