This is essentially what systemd-resolved with the nss-resolve NSS module is right? It’s possible to use /etc/nsswitch.conf to entirely disable the built-in DNS resolution in glibc if you want.
It's still a bit worrying, with manual JSON parsing: https://github.com/systemd/systemd/blob/79f487038444646f5bce... But at least it's just ~600 lines of fairly straightforward code.
You also can get most of it with nscd.
(Sigh, I wish BUS1 guys pushed their project to completion)