Any updates on this?

[lukaszmoroz]

The repo has not been maintained for 3 years now, there are some never released symbols (#7).

Are there any forks? Alternative fonts with similar symbols?

[a-usr]

Powerline extra has moved to Nerd Fonts. Sadly the symbols youre talking about aren't there either

[Finii]

Added that glyphs to Nerd Fonts (still a PR) as

• Add inverse powerline arrow heads nerd-fonts#1490

I need volunteer testers, please see that PR for details.