Sometimes I wrap these in a some very simple chatgpt code to import the collection / nodegroup(s) i want to make them easier to use. That is if I can’t make them import as smoothly as I want with the Asset Browser alone.
If its just for you dont worry about it. Just continue using them as legacy addons, otherwise convert it into an extension. Writing addons/extensions has not really changed (much), the way they are integrated has slightly changed. For small scope addons more or less just the addons bl_info moved to a manifest file and they are nested in another directory, Imports and alike also slightly changed. Have a look here: