my takeaway from the article is I hope OP isn't responsible for that lag fest of an animation[0]. I hate embedded stuff that takes ages to animate while the hardware obviously just can't handle it. Skip the animation, and just make it snappy, damn it! There's nothing more infuriating than a slow interface that makes you wait needlessly.
[0] https://blog.benjamin-cabe.com/wp-content/uploads/2021/10/re...
OP here :) That animation is laggy on the Renode emulator (at the moment at least), but definitely snappy and 30fps on the real HW...
Off topic -> but on topic of the original post. Do you know if https://github.com/ocornut/imgui is available for embedded? It might be too much for the very low end but it for a reasonably capable system it's better than web or some high powered UI like Qt.