I found on Wikipedia that Unicode has these characters: Left one eighth, Left one fourth, left three eighths, etc... (U+2588 through U+258F)
▏▎▍▌▋▊▉
It doesn't seem to contain the "right" equivalent of those. Is there some trick to displaying blocks with the right-half filled?
The right blocks are defined as of Unicode 13.0 released March 10, 2020.
They may display below depending on browser font:
U+2590 ▐ RIGHT HALF BLOCK
U+2595 ▕ RIGHT ONE EIGHTH BLOCK
U+1FB87 RIGHT ONE QUARTER BLOCK
U+1FB88 RIGHT THREE EIGHTHS BLOCK
U+1FB89 RIGHT FIVE EIGHTHS BLOCK
U+1FB8A RIGHT THREE QUARTERS BLOCK
U+1FB8B RIGHT SEVEN EIGHTHS BLOCK
References: