Hi,
Objects in Range: 70,000,000-74,999,999 for Business Central Online Only. A on-prem Customer cannot install extension with objects within this range.
For You Steps will be (AFAIK) -
1. Reach out to Microsoft to get purchase a new range of objects 1,000,000-69,999,999.
2. Check with Microsoft that will it be a valid update if you change the object Number Microsoft will not have a problem.
3. If yes, then renumber your extension objects with New Range (that works on On-prem and SaaS - 1,000,000-69,999,999).
4. Then republish your app to AppSource for validation as update.
5. After app is live in AppSource then you can share app file for on-prem customers.
This is technical possible because Object No can be changed and it's not a destructive change.
Hope it helps.