HTTPS backends are in the next build but usually you don't need it (HTTPS backends are usually for applications that support only HTTPS). The Frontend (server) supports HTTPS since the beginning (for example if you want to listen on TCP/443 for HTTPS - which supports HTTP/2 BTW).
The process will require 4 MiB more space.868 KiB to be downloaded.Proceed with this action? [y/N]: y[1/3] Fetching os-nginx-devel-0.4.txz: 100% 26 KiB 27.0kB/s 00:01[2/3] Fetching nginx-1.14.0_10,2.txz: 100% 524 KiB 536.6kB/s 00:01[3/3] Fetching brotli-1.0.5,1.txz: 100% 318 KiB 325.5kB/s 00:01Checking integrity... done (0 conflicting)[1/3] Installing brotli-1.0.5,1...[1/3] Extracting brotli-1.0.5,1: 100%[2/3] Installing nginx-1.14.0_10,2...===> Creating groups.Using existing group 'www'.===> Creating usersUsing existing user 'www'.[2/3] Extracting nginx-1.14.0_10,2: 100%[3/3] Installing os-nginx-devel-0.4...[3/3] Extracting os-nginx-devel-0.4: 100%Stopping configd...doneStarting configd.Keep version OPNsense\Nginx\Nginx (0.0.0)Reloading plugin configurationConfiguring system logging...done.Reloading template OPNsense/Nginx: OKMessage from nginx-1.14.0_10,2: