I would like to program SailfishOS applications. But, I would prefer not to use QML, C++, or Python.
I'd like to use something like Rust. But, I'm not sure how to know what options I really have.
What kind of things should I know to be able to determine what compilers will create binaries for ARMv7hl?
You can't really avoid Qt, but with C++ that trick is possible. There was a thread on Devel mailing list. All you need is to find good Qt5 bindings for Rust. These look promising.