And in any case, C++ is always a better option than C regarding safety, when nothing else is available.
Go's runtime can be a showstopper, especially for multi-language projects.
C++ may be better than C, but many people feel that Rust is even better.
Rust is already available in almost all scenarios, there's no need to wait for it.
While it's safe to assume that C gets a decent amount of use on every platform, you can't expect all platforms to be as well-supported as the major ones. Undoubtedly, some of those platforms would be listed as low-tier if the C compilers cared to maintain a platform tier list. But a platform being low-tier doesn't mean you shouldn't use that compiler there.
As for trusting Rust or C on niche platforms, C is so full of UB, platform-specific choices, and vendor extensions, that it's hard to ever fully know how well this or that project will work. Rust is much less surprising, if it works at all I expect it to fully work. I'd definitely pick Rust on niche platforms if I have the choice.
While not as safe as Rust, it is definitly much safer than plain C.