Vapor, Firebase, Microservice, ...? What to user for big app.

Hi. I use laravel for my applications and normally my apps are not so big. I'm planning now a new app. If it works i will got very much user, with every customer. So if a customer comes to my app he brings for example 50k-1m users. Now I think about how to build my app.

It will be a mobile app build with nuxt. My normal way would be to build a backend with laravel. But is this stable for so much users? Can I scale it? I saw that there is a new service called vapor. Or should i do something like firebase. It seems that firebase are multiple microservices, if Im right?! ...

Sorry. Till now I just used my hosting like in 1999 :P ... sometimes i use s3. What would you say is the best. I would prefer to go with laravel, because I know the system. Last thing: I'm more a growth hacker. That means I build it and if it works i go and find other people who will help me. So i use a lot of services like algolia instead of elastic search, pusher instead of build my own socket system, ... so I just want to be sure, that im not developing something, which cant be used later if it works.

hope somebody can help and know what i mean :) thx.