Wow, I hadn't heard of SIGIL 1, much less SIGIL 2, so Romero is making new episodes of Doom/Doom 2? Crazy!
The first Sigil is one of the curated mods in the Doom remaster on Steam and AFAIK also consoles (I only own the Steam version but I think the other platforms have feature parity), so there isn't even a need to use it with GZDoom or another source port.
I appreciate info! I'll check out the Doom Remaster on Steam!
If Romero and Carmack aren't among your personal heroes, you've misunderstood something about the world.
Here is an alternative Piped link(s):
https://piped.video/watch?v=lBdKTqfSy_E&t=820s
Piped is a privacy-respecting open-source alternative frontend to YouTube.
I'm open-source; check me out at GitHub.