supervise-daemon is still experimental, has bad defaults and tends
to be unreliable. Users can enable supervise-daemon, if they want to,
simply by declaring `supervisor=supervise-daemon` in
/etc/conf.d/connman.

See my mail from Tue, 15 Dec 2020 15:33:16 +0100 in alpine-devel
mailing-list in topic "Use of supervise-daemon in Alpine".
(I cannot simply reference it from ML archive because it's broken.)