I'm not sure if anyone else has this requirement, but when moving from Photos to Lightroom Classic, I set up a hierarchy of keywords for each album that included the folders that that album was in. e.g. I set up keywords such as "Conferences>2019>FOSDEM>All" and "Conferences>2019>FOSDEM>Selects", etc. in Photos which were then picked up by Lightroom as a keyword hierarchy.
I then wanted to create collections inside collection sets from this keyword set, so I wrote a plug-in to do this for me.
If anyone else has this requirement, then maybe https://github.com/akrabat/collection-creator-lrplugin will help you too.
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