Debian riscv64 port status
Given than the arch-dependent packages are about half of the Debian[‘s main, unstable] archive and that (in simple terms) arch-independent packages can be used by all ports (provided that the software that they rely on is present, e.g. a programming language interpreter), this means that around 90% of packages of the whole archive has been available for this architecture from early on. And, of course, all other contributors of Debian help by keeping good tools and building rules that work across architectures, patching the upstream software for needs of several architectures at the same time (endianness, width of basic types), many upstream projects are generic enough that they don’t need specific porting, etc. Currently there are more than 500 packages from the Rust ecosystem in the archive (which is about 4%), and they cannot be built and used until Rust has support for the architecture.
Source: people.debian.org