libSDL2pp VS halley

there are cpp wrappers https://github.com/libSDL2pp/libSDL2pp

API seems reasonable. I was just trying out libSDL2pp but it lacks some functions like DrawCircle etc.

But this is normal with C++. It is close to C in which major "infrastructure" libraries are written. There might be a C++ wrapper for them, in this case, current one seems to be libSDL2pp

SDL2 is a C interface, so there's no objects (thus no OOP). There's SDL2pp which wraps it in a C++ interface, but honestly you shouldn't worry about that yet. Learn OOP from school and start to apply it as you get comfortable with it, for now just stick to the C interface and focus on #1.

https://github.com/amzeratul/halley if you want 2D

Given that the game is being written with their in-house engine called halley which supports consoles (was used for Wargroove), the answer is most likely yes.

Halley Engine - C++ Game engine used in Starbound, Wargroove and the Upcoming Witchbrook

It was originally in another programming language called Rust, but the programmer that knew that program left. Amzertul made an amazing engine with Wargroove called halley and we felt that it would be perfect for WB. Focus was shifted to Wargroove for a while, and then witchbrook started to be recoded. At this time the artstyle was changed to isometric.

Not pixpil, but our own engine which we use to make pixel art titles is open source.

We used my own game engine (Halley) for both Wargroove & Witchbrook, no regrets at all! It's definitely a lot of work, but owning the entire stack gives you a lot of advantages. I posted a Twitter thread with my thoughts on the pros and cons a while ago, if you're interested.