Help me validate micro SaaS idea

Hi everybody, long time lurker here.
As a technical person (developer) I do have some issues finding a good idea to work on in my free time, but inspired by a task that I had in the past at one of my jobs I think I might have found something but I need your feedback.

So, getting straight to my idea, it will be a micro saas which will offer a so-called App Inbox which you can integrate in your mobile application and/or website, using API's, and of course if things are going well I would work on some SDK's (Web, Android and iOS) for easier integration. It will also offer a dashboard for non-technical users to publish messages for their clients as well as an API for automatic integration on the publishing part.

There are of course tons of other providers in the market, but all of them are providing also push notifications and email and/or sms, which are more expensive.

What do you guys think ?

More about what's an App Inbox :
https://www.leanplum.com/blog/app-inbox/#:~:text=Essentially%2C an App Inbox is,gone once you open them.

https://xtremepush.com/how-an-app-inbox-can-enhance-your-mobile-marketing-campaigns/