I'd like to bring it to this groups attention that some of the powerline symbols are getting reviewed for consideration in unicode:
https://www.unicode.org/L2/L2019/19068r2-powerline-syms.pdf
http://www.unicode.org/L2/L2019/19343-script-adhoc-recs.pdf

Recommendations: We recommend the UTC discuss the proposal and accept the following three
characters, with code points in the (new) Graphics for Legacy Computing block:
U+1FBCB VERSION CONTROL BRANCH SYMBOL
U+1FBCC COLUMN NUMBER INDICATOR
U+1FBCD LINE NUMBER INDICATOR.

From my understanding, they ruled out the lock icon in favor of the emoji lock and claim that existing drawing elements suffice for powerline needs. Reviewing https://en.wikipedia.org/wiki/Box-drawing_character, I'm guessing they think the following are sufficient alternatives to powerline block drawing glyphs:

Box Drawing vs Powerline PUA

• ╱ \U2571 vs \UE0BB and \UE0BD
• ╲ \U2572 vs \UE0B9 and \UE0BF
• ◢ \U25E2 vs \UE0BA
• ◣ \U25E3 vs \UE0B8
• ◤ \U25E4 vs \UE0BC
• ◥ \U25E5 vs \UE0BE

Miscellaneous Anglebrackets

CJK Symbols and Punctuation vs Powerline PUA

• 〈 \U3008 vs \UE0B3
• 〉 \U3009 vs \UE0B1

Miscellaneous Technical vs Powerline PUA

• 〈 \U2329 vs \UE0B3
• 〉 \U223A vs \UE0B1

Diongbats vs Powerline PUA

• ❬ \U276C vs \UE0B3
• ❭ \U276D vs \UE0B1
• ❮ \U276E vs \UE0B3
• ❯ \U276F vs \UE0B1
• ❰ \U2770 vs \UE0B3
• ❱ \U2771 vs \UE0B1

Geometric Shapes vs Powerline PUA

• ◀ \U25C0 vs \UE0B2
• ◄ \U25C4 vs \UE0B2
• ▶ \U25B6 vs \UE0B0
• ► \U25BA vs \UE0B0
• ◖ \U25D6 vs \UE0B6
• ◗ \U25D7 vs \UE0B4

Legacy Computing (https://www.unicode.org/charts/PDF/U1FB00.pdf) vs Powerline PUA

• 🭬 \U1FB6C LEFT TRIANGULAR ONE QUARTER BLOCK vs \UE0B2
• 🭮 \U1FB6E RIGHT TRIANGULAR ONE QUARTER BLOCK vs \UE0B0
• 🮤 \U1FBA4 BOX DRAWINGS LIGHT DIAGONAL UPPER CENTRE TO MIDDLE LEFT TO LOWER CENTRE vs \UE0B3
• 🮥 \U1FBA5 BOX DRAWINGS LIGHT DIAGONAL UPPER CENTRE TO MIDDLE RIGHT TO LOWER CENTRE vs \UE0B1

Supplemental Symbols and Pictographs vs Powerline PUA

• 🤇 \U1F907 LEFT HALF CIRCLE vs \UE0B7

There's some discussion around the legitimacy of the powerline glyphs as needed block drawing elements in this proposal. It may behoove the community to work on a new proposal to include the extra glyphs as block drawing elements under the Graphics for Legacy Computing block, i.e. https://github.com/ryanoasis/powerline-extra-symbols.

Unicode has nothing approximating RIGHT HALF CIRCLE that could match \UE0B5
\UE0C0 onwards have no similar pre-existing unicode glyphs