as we, sad people in this forum call, the 3DGS is undead.

it really depends on you what you want to do, 3dgs might be okay, but do not invest in it. I expect only rare minor updates, mainly bug-fixes, nothing more, ever... it is okay for low system requirement pc only little fun games, or for toying, but Unity can do that too, or even better visual quality more easily, for free, where you have the option to move further, dig deeper, without an engine switching.

I am currently porting my stuff to UE4 (but doing some prototyping still with 3DGS), which has also some beginner friendly parts (visual scripting, visual custom "entity" creation , free assets, thousands of detailed tutorials, several game templates to start with, example games), but its C++ programming side is harder than Lite-c or Unity Javascript/C#, but it might not nedd you at all. Personally I need it, beside access to engine source, and after some experience UE4 C++ becomes a clever friend. Maybe UE4 system requirements are higher than Unity, but significant performance optimizations have been done recently, mainly affecting complex scenes.

moreover, the game you linked would be not easy to make with 3DGS.