As someone who has never used c++, it seems like it's primarily useful when latency and performance really matters and the cost of that is ease of use when it comes to developer quality of life/productivity.
I'd like to play with many gadgets, small embedded toys. Let's say it is custom a USB mouse. You may want to create a data structre that 1-1 represents whatever data you're pushing to the wire and the exact amount of time it takes you to push it over the wire.
C++ lets me abstract things better than C. There is a level of control in C++ where you get the decide to the minute detail how the compiler builds your software. With a C++ compiler you can say to the compiler to optimize one function, while not the other one in the same source file. Yes, the standard language abstracts the underlying machine and it will suprise you since compilers obey it very well if you not tell them otherwise. But all of the C++ compilers, including the niche ones, also let you pierce through those abstractions by special attributes and linker directives. So you can have an almost assembly code next to very abstracted and crazy optimized code.
C++ doesn't care how you build software, it is up to you to decide which kind of libraries, which libraries, what subarchitecture, what optimization level to use for each library. These sound crazy but current literature and internet is full of detailed documentation how to do these things since somebody at some point needed to do them to debug a particle accelerator or the latest PCIe bus or something and it is somehow useful for your stupid USB mouse.
Rust as the language (syntax, rules) is better. Rust articulates better, it makes a lot of sense. However to appeal the newcomers and people who look different sa(n/f)er ways to do things, Rust generally limits you. You need to codify certain "features", or you need build.rs files. You need to find underdocumented or "nightly" features. Whatever you come up with would be better formally defined. However going against the grain of Rust and Cargo creates abominations.
Notably a hobby http server, or a compiler, or an emulator, are projects that i enjoy/ed particularly and to which C++ is a good language choice, generally.
kv-api is a kv store with a REST api, for example, which is more unusual to write in C++.
[0]: https://github.com/lionkor [1]: https://gitlab.com/lionkor
Compiler development, in case you plan to play with GCC or LLVM as infrastructure.