It is viable just fine as it is, i'm not sure what you have in mind.
In any case C++ support for Lazarus is almost impossible due to the work needed and the projects that will need to cooperate - i go into details here: https://news.ycombinator.com/item?id=15893362
I think most people, certainly me, who would be looking for a Pascal compiler are trying to avoid C++ like the plague.
It’s funny when you read about languages like Rust and Go basically trying to undo decades of C-induced damage, reinventing (albeit also exceeding) thangs that Pascal/Modula/Eiffel already had.
Yet, it would be good to have an open source alternative to C++Builder. In other words, besides Pascal, to also have an option for a mainstream [native] language.
In any case C++ support for Lazarus is almost impossible due to the work needed and the projects that will need to cooperate - i go into details here: https://news.ycombinator.com/item?id=15893362