There was an issue in Bugzilla (https://bugzilla.gnome.org/show_bug.cgi?id=781597) that no one cared about, I just checked it every 6 months and saw no progress, so I thought I should add it to Gitlab so that people like me who are used to checking it every 6 months don't lose hope:
It's been a long time since font ligature is introduced (https://en.wikipedia.org/wiki/Typographic_ligature), Terminal.app, iTerm.app in macOS and Konsole in Linux support it (among others).
Ligature is used in some monospace fonts to help with programming in terminal, an example of such font is FiraCode: https://github.com/tonsky/FiraCode
It would be nice if vte support it so that all the terminals that use vte can have this feature. Otherwise we'll just check this issue every 6 month to make sure nothing has happened about this issue.