It’s a good candidate since it sounds like there’s no precision mechanical components like there would be in a hard drive. Does anyone have ideas for how I’d go about this? Is there a barrier I’m not considering?

I know how to make basic semiconductors already, so that’s not an issue.

Edit: I’ve got an answer written down in the comments now. TL;DR you’d still need lithography to do it the OG way, because of the patterned magnetic material that directed bubbles around the medium, but material requirements are actually pretty flexible.