There's a new attempt at safety profiles. I'm not enough of an expert or read in enough on this proposal to answer your detailed questions, but there's a lot of words by Sutter and Stroustrop on the proposals:

Stroustrop, 2023 presentation: https://open-std.org/JTC1/SC22/WG21/docs/papers/2023/p2816r0...

Sutter, 2025 committee paper: https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2025/p30...

Sutter, 2024 blog post: https://herbsutter.com/2024/03/11/safety-in-context/