There are numerous tutorials on running your own private certificate authority (CA): * https://smallstep.com/blog/private-acme-server/ https://smallstep.com/bl

There are numerous tutorials on running your own private certificate authority (CA): * https://smallstep.com/blog/private-acme-server/ https://smallstep.com/blog/private-acme-server/ ; https://smallstep.com/blog/build-a-tiny-ca-with-raspberry-pi-yubikey/ https://smallstep.com/blog/build-a-tiny-ca-with-raspberry-pi... * https://openvpn.net/community-resources/setting-up-your-own-certificate-authority-ca/ https://openvpn.net/community-resources/setting-up-your-own-... * https://www.digitalocean.com/community/tutorials/how-to-set-up-and-configure-a-certificate-authority-ca-on-debian-10 https://www.digitalocean.com/community/tutorials/how-to-set-... Import the CA's root cert on your browsing devices and anything it issues will be trusted.