Where to host spring boot app?

I’m making an app for personal practice. It will be native android and also web using react. I’m planning to do an API that will have authentication and store data based on the user… Now, I’m new in backend and I have an idea of how to implement all of this. Basically I want to use AWS cognito for the authentication, but I don’t know what other service of AWS use to host the spring boot app. Also, I’m now sure if it’s worth to use dynamoDB to store the data, or implement MongoDB or even Postgres inside the app… Any idea or suggestions is welcome. Sorry if I got the wrong concepts, I’m still learning about cloud and this is new to me.