I personally don't look at it like a mega dungeon, but more of a "Poke your head in, explore, and then come back to the city" type loop. Then it's a lot less stressful, at least to me

I'd be a huge fan of that!! Current options are overwhelming and I personally find it very difficult to filter through. It'd help highlight high quality work, or at least it'd be nice to have another way to support works you like

I personally love the roll under system, but I get that it trips people out, since most people are used to static DCs. But if it helps the table, then that's a win!

Yep! Something like that. And a SUPER easy one is simply roll with advantage. If a 2d6 system, roll 3d6, drop lowest.

I'll add on one last one. Dungeon Crawl Classics and the dice chain! Tags can be used as a reason for a character to roll higher or lower on the dice chain (e.g. d24 instead of a d20 or a d16 instead of a d20, etc.) The same concept could be used for any game, too

Basically, a label that provides a boon/bane.

Freeform Universal's "Descriptors" does a good job explaining how a tag system can work. City of Mists, FATE's "aspects", Whitehack, etc. Discworld is another good example. They can also be used to represent things like relationships and abilities too!!

For custom skills w/ Mark of the Odd games, I do what Ben said and link it with downtime or something that narratively makes sense.

For incorporating, I use a tag system! and provide a bonus/advantage when a player uses that skill, or sometimes ONLY allow those w/ the skill to perform the action