Oh wow, that was easier than I’d expected.
CentOS 8 comes with Apache 2.4.37 and mod_http2 was already loaded (in /etc/httpd/conf.modules.d/10-h2.conf)
All I had to do was add “Protocols h2 h2c http/1.1” to /etc/httpd/conf/httpd.cond (I put it directly after the ‘Listen’ line).
All sites are now serving requests over http2
It would be nice to have an option in the GUI for ‘Protocols’, if there isn’t one already?