Should all software work on V7? No. But there are some basic libraries and tools, that should be really portable. For those few projects, v7us is a great testbed.
An alternative is running V7 in a pdp11 emulator, but the original (and only one) C compiler of V7 is so obscure that most C programs we have nowdays wouldn't compile without a massive rewrite. With v7us, target is having your software compile against v7libc using an ANSI C (C89) compiler while using sed, grep, awk, make of the late 70s.
v7us has all the shell tools you'd expect, including awk, sed, [ef]grep, yacc, lex, make, diff, diff3, etc. Still missing: