So if the bootloader can now be unlocked, then it becomes feasible to make a custom ROM for this device, but that is only the first step.
/e/OS is built on LineageOS, so it would be possible to build an /e/OS ROM if a LineageOS ROM existed. I believe that LineageOS builds on AOSP. At the moment, as far as I can tell there is no AOSP or LineageOS build, and I don’t know if anyone is planning to start trying to make one. So an /e/OS ROM is still not feasible.
To get any custom ROM for this device, someone would need to be motivated, and prepared to spend a lot of time and effort (with no guarantee of success) to making first an AOSP ROM. If / when that is done, then a LineageOS ROM would be possible (assuming someone is prepared to spend a lot of time etc…). Only after that would building an /e/ROM be feasible.
To give some idea of what is involved just in building and AOSP ROM see this web page
https://appuals.com/build-custom-rom-android-open-source-project/
Note the first warning
It should be noted that this is a massive undertaking – if you have zero experience in coding or fooling around in Linux terminals, you may want to get some knowledge under your belt before diving into this deep-end.
If you get over that, another big obstacle will be getting hold of all the proprietary binaries needed to make the device-specific hardware work. This device isn’t currently on Nokia’s list of open source phones, so there’s no help there.
https://www.nokia.com/phones/en_int/opensource
I am sorry to be negative about this: I’m sure this is a great device, but I’m not sure this is the right place to look for people prepared to put in the needed work to make a custom ROM. Most people here are interested in getting e/OS/ working on devices which already have custom ROMs built.Your best bet may be to contact whoever made the video you posted. If they are interested in unlocking the bootloader they may be interested in taking the next steps.
Good luck!