So my question becomes, why Unity? It has one advantage I see: A giant body of users. But that's about it? I could be wrong and super look forward to your challenges.
C# has performance issues, and can't multi-thread. It also forces you to do all of the coding in syntax.
C++ is clunky, but far more versatile. You can do literally anything in it, with better performance. Unreal has a smaller but quicker-growing base of users. It also has blueprints to allow you to avoid coding for redundant tasks, or to outsource some simpler coding projects to other team members while you do the heavy lifting.
I only ask because a) I went through the same questions to myself, and b) if you haven't really gotten started yet, why start with Unity? There could be awesome reasons! It might benefit me for future game projects too.
Either or, as gamedevs on the side, we can bounce ideas off of each other nonetheless
Looking forward to it partner!