I think I know how that method you did worked. the way a lot of uploaders have continued to dump games is by downloading them on the latest firmware to an external hdd, then plugging the external hdd into an exploitable system after running hen. sony tried to do something about that with 7.xx, but it was patched with hen. sony has done something like this again with 8.50, which obviously isn't patched as of yet, but if we can dump the kernel, it will likely be patched. we just need an exploit.
Yes you can install games externally on the latest firmware, and mount those games on a exploitable console, and dump them as long it uses keys bellow fw 7.55, one of things harder to get are dlc, with this method is fairly easy, also if you have the disk games, or live in a country were rental is allowed for a week as an example, you can dump as many games you want and very cheap.