You can attempt to use a BallPivot algo (but if the pts distribution is “not even” (or not “skin deep”) don’t expect very good results - if any at all). Of course contemporary BP is not the thing as invented by IBM Labs years ago … but I doupt that you can find source code that works (and is fast).
That said I have C# stuff that does 3d convex tri meshes (given any collection of points be these “evenly” spread or not: the recursive technique for that shares some points with the classic 2d convex hull algos). It would require major changes and/or several lines of code more in order to make - fast - a 3d concave mesh .
BTW: Are you familiar with algos that do 2d concave hulls?