Hello @Sayyed Adeeb , thank you for reaching out.
In the above scenario, there can be two possibilities that we can leverage to make users from some other tenant (in this case User2Tech tenant) to access apps developed in your tenant i.e User1Tech.
- Create a multi-tenant app.
- Add Users of the other tenant (User2Tech tenant) as guest users to your tenant.
Now let me elaborate on the above two options.
Creating a multi-tenant app is the most favourite amongst the two options provided. As creating a multi-tenant app in Azure Active Directory, can be accessed easily by hundreds and thousands of users belonging to different tenants. You can read more on the multi-tenant App architecture here:
Both the links shared above are a good read to understand the multi-tenant architecture.
The second option of adding the users from other tenant is also a possibility, in case your app is a single-tenant app. But then it loads up your own Azure AD directory by adding numerous users from other tenants as guest users in your own tenant. I would recommend you to avoid this as much as possible.
In case you have a single tenant app, its advisable to convert it to a multi-tenant app and that would be ore suitable in the long run too.
Hope this helps.
Do let us know if this helps and if there are any more queries around this, please do let us know so that we can help you further. Also, please do not forget to accept the response as an Answer; if the above response helped in answering your query.