I'm not sure that source code is going to be mega useful, with it being built on construct 2, at least from what I know about construct 2 (idk if it changed), it's not going to have generated particularly readable or maintainable code, and probably why open-sourcing it would be a herculean effort. The alternative would be releasing project files, but then there's the issue of the game still being built on a dead program.
If the project were to go on with a larger scope, it would probably be worth just rebuilding from the ground up on a different engine / language using the assets. It's obviously not unheard of; everything made on construct is JavaScript, and game dev tycoon (probably an inspiration for this game) was written in JavaScript, but it's in general a bit of a niche choice for games.
Viewing post in State of the project + Mod Tool release comments
Unreal Engine was made for 3D games, I wouldn't recommend it for a 2D game like this. Besides, Godot is entirely free. Zero ads, zero revenue cut, zero paid features, entirely open-source. Godot is funded entirely on donations and has far better 2D functionality and performance compared to Unity & Unreal Engine.