Hi mk6,
For help with silencing Apple Watch stand notifications while allowing other notifications you may want to set a custom focus. The article here has more information to assist. Use Focus on your iPhone or iPad - Apple Support
Without Focus and Do Not Disturb stand notifications will continue to be delivered. If you'd like you can turn the feature completly off with the steps foudn below and in the article here: Use the Activity app on your Apple Watch
"Set activity reminders
- On your iPhone, open the Watch app.
- Tap the My Watch tab, then tap Activity.
- Choose your notifications and reminders. For example, coaching notifications are based on your previous progress.
"
While there's no way to set a schedule for the reminders to turn off, you can submit additional feature feedback here: Product Feedback - Apple
Cheers.