This scenario is possible.
We don't have to provide a new manifest file (for store submission) every time we want to update our web-app service. We can simply update the web-app service and let the submitted manifest file untouched if we doesn't need any changes in this manifest file.
Ref Doc:
- https://learn.microsoft.com/en-us/microsoftteams/platform/concepts/deploy-and-publish/appsource/prepare/submission-checklist
- https://learn.microsoft.com/en-us/office/dev/store/add-in-submission-guide?toc=%2Fmicrosoftteams%2Fplatform%2Ftoc.json&bc=%2Fmicrosoftteams%2Fplatform%2Fbreadcrumb%2Ftoc.json
Thanks,
Nivedipa
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