If you were going to build a house, and could only pick one tool, which would it be? You need several tools, but woodworking tools work best for 90% of all houses whereas steelworking tools are limited to a much different type of building. Stick with what's popular and common, some techs will have more open and supportive communities than others.
I'd place a goal or milestone in your roadmap - you will learn the tech along the way - make something that you want.
To be honest, you're trying to cram 5 years and 3+ complicated techs into a beginner project; some languages and platforms are actually re-usable... e.g. If you use React Native and MERN backend, you only need to learn Javascript. Your proposal has 3+ langs, but they're wildly different in terms of code/debug/deploy in the real world.
I'd place a goal or milestone in your roadmap - you will learn the tech along the way - make something that you want.
To be honest, you're trying to cram 5 years and 3+ complicated techs into a beginner project; some languages and platforms are actually re-usable... e.g. If you use React Native and MERN backend, you only need to learn Javascript. Your proposal has 3+ langs, but they're wildly different in terms of code/debug/deploy in the real world.