Lanefan
Victoria Rules
Mileage varies greatly on this. Never mind that rather incomplete list is missing:Again, I don't think downtime is a separate pillar. Looking at Xanathar's list of downtime we have.
1. Buy Magic Items(exploration/social)
2. Carousing(social/combat/exploration)
3. Crafting an Item(exploration/social)
4. Crime(exploration/combat/social)
The depth of the downtime activities is not going to be as great as non-downtime, but the activities, rolls and results fall into the big three pillars.
5. Stronghold/temple/lab/base design and construction*
5a. Ongoing management and financing of same
6. Research and invention
7. Training* and levelling up
8. Treasury division and allocation
9. Non-adventuring travel to known places e.g. to visit family
* - 5e doesn't have these in RAW but some other editions do, and even though 5e codified the pillars this is an edition-agnostic topic.