Can I use or share my own Meta Setup & WhatsApp Business API Account to send messages to customers of my customers through my android app?

Question

Goal: I want to provide WhatsApp messaging feature within my android app for my customers to send messages to their customers, and without my customers intervention in terms of any accounts setup/embedded signups for them. Because my customers won't use this feature if they need to invlove in the setup process that Meta docs are suggesting as a solution or tech provider. So I want to use my own setup and WABA account so that my customers can use this feature right way.

My Setup:

1. Meta developer account is created.

2. Meta business manager is created.

3. Meta app is created and linked to business portfolio.

4. My business verification is successfully completed.

5. WABA Account is created and my new business phone number is added and Webhooks setup also done.

6. Access Verification is not done as I am not going to deal or create my customers WABA accounts.

7. App Review submission is failed as I didn't provide FB Login button and now I think I understood why FB login is needed and now I don't want my customers fb login intervention as it is going to come to the concept of dealing customers WABA accounts in the end.

8. Added Phone number is in unavailable status, its registration is failing because of on premises api expiration and struggling to do it with Cloud API endpoints like /wabaId/phone_numbers, /request_code, /verify_code etc and now I completely got stuck and confused on how to register business phone number with certificate code and without issues.

Test implementation in the app:

1. Multiple messaging templates are created and available to use.
2. We are able to send whatsapp messages using templates created to the mobile numbers added in the test list in development mode.

Problems/Concerns/Queries To achive my goal mentioned above:

1. Is my goal achievable?
2. How to register added business phone number using certificate code as per latest docs/changes?
3. Does it require access verification to register business phone number?

Please help me with my goal and what else I need to do or am I missing anything?

Currently added business phone number is in unavailable status and need to get it to active status.

I am assuming that I don't need to go through access verification and app review process as I'm not going to deal customers individual setup/waba accounts.

I am expecting to use my business phone number id with permanent access token to make graph API /messages calls and send messages to customers of my customers. This will be triggered by my customers through my android app.