Vivy
A free and open source battery themer that's actually good!
After the disaster that was my previous battery themer (Juiceless) I decided to make one that fills dynamically, includes user options, and only requires a single png instead of 20, and provides a suitable FOSS alternative to the avaricious paid tweaks that are all too common these days. Enter: Vivy.
Vivy makes it easy to create your own theme. You only need one (1) png (/Library/Application Support/Vivy/yourthemename/icon.png) and the ability to compile a deb. Vivy does the rest, including horizontal, vertical, or circular battery fill by percent, colourise the icon when charging or lpm, show the current battery as a percentage, and choose between multiple themes installed at the same time.
Also, I should give credit to the designer who made linear, the default theme here. I can't seem to recall who it is though. When you're as famous as I am, you meet so many people it's impossible to remember them all. What is that guy's name? It's on the tip of my tongue... yeah, idk, I want to say... timeloop?