Is it still possible to develop a multiplatform videogame from scratch in 2025?
Meaning with no pre-made engines and the least amount of dependencies?
Sadly less and less devs are doing it and this is choking technological innovation, making it a privilege reserved for very few top studios and specialized companies.
According to this article it can even be a good idea.
And have a look at Animal Well and Tiny Glade: they did it and it worked very well for them!

The Owl is watching