You can enable http/3 just fine even if you also serve clients that are falling behind on web standards, as long as you also serve http/2 as a fallback.
Safari not supporting isn't a problem unless your business only and specifically targets Safari, and even then it's a relatively painless way to help the few customers who run preview versions get a nicer experience.
Safari not supporting isn't a problem unless your business only and specifically targets Safari, and even then it's a relatively painless way to help the few customers who run preview versions get a nicer experience.