Add-ons are only available for the desktop app, but they can have effects on your collection - which will also show on mobile when you sync.
These are the add-ons with effects on mobile:
- Special Fields
- Image Occlusion Enhanced
These add-ons just show extended stats on the desktop app and do not have any effects on your collection:
- Review Heatmap
- True Retention
The following add-ons are obsolete, as recent Anki versions have a native implementation of each of their features:
- Customize Sidebar
- Hierarchical Tags
I’d love to know where you got that list of add-ons from. Were they recommended in a YouTube tutorial?
Add-ons, even really good ones like Image Occlusion, aren’t essential by nature. It really depends on the type of work you want to do with Anki. I recommend you try out the vanilla Anki experience and only install add-ons when you feel the need for them - small things like Review Heatmap can’t do any harm though.