Quite interesting, that the author uses code which looks more like C than C++ :) Anyway, there is also a second part too: https://craftofcoding.wordpress.com/2021/04/02/c-versus-ada-for-safety-critical-software-ii/

There is also available free version for FOSS developers, you have to contact with Shawn Fanning, sfanning@ptc.com for it. As far I remember, the developer of Globe-3D is using that version of ObjectAda.

And contact sales, that's standard :) AdaCore is doing that same with GNAT Pro.