Edit: I ended up abandoning the default WSL Ubuntu console and moving to Windows Terminal by following the instructions here, and now everything is working.
I installed Oh-my-zsh on WSL 2 (Ubuntu 20.04 if it matters), and I get question marks instead of whatever should be in the prompt. It looks like this (theme is set to "agnoster"): Question marks
I looked it up and the most prevalent advice was to install powerline fonts, so I followed the instructions here: How to install Powerline fonts on WSL?. I indeed was able to set the font to a powerline font in the settings of the console, but the problem wasn't solved (I tried to restart my computer and it still didn't work).
I saw similar questions about iTerm but I couldn't extract from there relevant steps that I can take.
Any advice?