You can maintain a Background Bluetooth connection on WatchOS for timely Alerts. You can refer to the WWDC2022 session named : "Get timely alerts from Bluetooth devices on watchOS". You will also need to add Bluetooth-central to UIBackgroundModes in your Watch app's Info.plist. If you have to send bluetooth traffic, then there is a limit on how long the watch can remain connected over Bluetooth when your app is in the background. I hope this helps.

Yes correct. The Apple Watch Bluetooth LE can only operate as a central device. If you have use cases where you need to be Peripheral, feel free to let us know, you file a feedback radar.