Have you released any finished projects yet? Trying to do two projects at once is a motivation-killer and is a common mistake that new devs make. If you have the time and resources to work on two games at once, go for it, but you may find you've drastically underestimated what that means once you get deep enough.

For what it's worth, I think Totally Not Black and White 3 is a niche that desperately needs filling and a decent game of that type would do quite well. If I were you I'd focus on that. Lionhead really dropped the ball with that franchise and nobody's picked it up. I would, however, be careful about making it too similar. You might run into legal problems down the line. I think if you avoid the whole virtual pet aspect - which I never liked anyway - you'll be fine.

If you want to turn this into a career, unfortunately Unity is by far the best way to do that. Godot has almost no hiring activity and I doubt it ever will. As much as Unity sucks, it's where the money's at. Of course, if you don't care about joining a studio and just want to do your own thing forever, Godot is a fine choice.