This is a response to the Rachel by the bay blog post https://rachelbythebay.com/w/2020/12/24/wg/ Personally I rarely use a mac, and don't do wg on demand, but one thing that did annoy me was being unable to set dns search domain, which wasn't mentioned in the blog post, but I believe is also caused by OSX deficiencies.
DNS search in MacOS is managed by their DNS infrastructure which is documented under resolver(5). That lets you route the resolution of particular domains to specified nameservers. The files live in /etc/resolver but can also be manipulated with scutil. So it's not an OSX deficiency, it's an OSX difference, similar to launchd vs systemd.
I can do this on the OSX networking tab where I set DNS server, but from what I read that feature isn't available for the wireguard client.