I really like the #Mastodon feature to combine hashtags in one single column.

1. search for #hashtag of your choice

2. click on the setting (slide control) icon in the upper right corner and chose "Pin"

3. Click on slide control icon again and add more hashtags and combinations

Done.

The feature was once discussed here:
https://github.com/tootsuite/mastodon/issues/6359

but it seems it hasn't made it into the documentation.