https – Content Filtering Certificate


He faced such a problem: The school has state internet with content filtering (on the provider side or where they do it) using the Internal Systems certificate, without which https connections don't work accordingly. For all this to work, this certificate is installed on each PC with my hands in the trusted storage. Now we decide to increase the Wi-Fi connection with the distribution of this Internet, but we have set the bar, because on mobile devices, this certificate does not exist, respectively, and nothing works, and putting it there, let's say, is not possible.
So the question is: can all clients on the network be hidden behind PfSense Similar gateway or another solution this certificate will be on, and to work from any device within the network, even if it doesn't is there a certificate there? Thanks in advance.