Note that -static is far from enough to do actual fully static builds (i.e., no libc).
See the gcc specs used by the musl wrapper (as well as the terse GCC manual on options affecting linking).
https://github.com/GregorR/musl-cross might be a good start to build such a TC?
CT-NG appears to have musl support, but I'm not sure how stable/tested it is. Same for BR, but @knc1 might know more there

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