That's not quite true. There are multiple vendors providing Ada compilers to industry: https://github.com/ohenley/awesome-ada?tab=readme-ov-file#co...

Ada compilers: PTC ApexAda, GreenHills Ada, Static analysis tools for Ada: CodePeer, ConQAT,Fluctuat,,LDRA Testbed,MALPAS,Polyspace,SofCheck Inspector,Squore,Understand. Similar list for all other things.

When C++ was chosen for F-35 there were more verification tools to Ada than C++.

For C++ on similar systems its becoming more and more "I hope you like LLVM with the serial numbers filed off". Lots of the tool vendors are sunsetting their bespoke compilers. Most of the vendor IDEs have always been Eclipse with a bunch of bundled plugins.