There are a few scenarios where using HTTP/2 without SSL makes a lot of sense. Relatively secure intranets is one of them, and website development is another. That said, you can still use HTTP/2 in your intranet by deploying SSL, and it is actually easier and cheaper in an intranet.
Usually there is much more control in an intranet, without any implied monetary cost. For example, you can setup a simple local DNS server (like DNSMasq or the one built-in into Windows) to have domains pointing to ip addresses, and configure, through DHCP, those addresses to be static.
The certificates issue is certainly more tricky. You can use the internal Certificate Authority of your client, if they have one already, or set it up for them.
And finally, if your client is so small that all the computers that will use your application are in the same building than the server, don't bother neither concatenating the files nor using HTTP/2.