For comparison: ripgrep (Rust) is >2 MB stripped, GNU grep is <200k stripped.
I have not looked at systemd in a while, but I'd be surprised it systemd in total is not smaller than the Rust runtime, which would leave your minimal subset larger than the original.
So maybe you meant something other than code size here, but using words like "minimal" and "subset" feel a bit (unintentionally, probably) misleading to me.
I'm sure the Rust people will at some point find a way to reduce the footprint of the runtime. Currently they have other, more pressing goals.
Personally, I wrote my own init system. The PID 1 process is a 10k statically linked binary. Resident memory size is 24k on one of my AMD64 Linux production servers. That is what I think could rightfully be called a minimal subset.