Would anyone else be interested in adding IL categories for each of the 45 contracts, including the Ace missions?

Obviously a lot of advantages can be brought in for any particular level but personally I think it'd be exciting to see just how fast someone can complete Omerta, for instance. It'd just require a new individual level leaderboard, and then either just have one category (or two, you could add an "including bonus(es)" category to have 2 per level.

Just an idea. I'm very interested in running this game but am finding it difficult to drum up the desire to do a whole 1hour 30minute full-game run. Being able to practice and get into some ILs would be an excellent starting point for me and potentially other runners.

I wouldn't be bothered by the addition of IL categories but I also don't personally see the appeal. The only true standalone levels in the game are the Ace contracts. Everything else is, in some aspect, tied to what you need to do before and after the contract for the sake of full-game runs. In that sense, I don't think doing ILs is necessarily great practice for new runners.

For example, the fastest way to complete the Mafia's "Foothold" contract would be to fly your parked helicopter over to pick up the NK truck, but then you wouldn't have a helicopter available near the HQ once the contract ends.

Combine that with the fact that cheats / NG+ would come into play for most contracts and that this game already has way too many categories as is, and I'd probably vote against this. Might be a nice addition if participation picks up in the future.

Also, if Any% runs are too lengthy for your tastes, I'd recommend trying the Any% NG+ category! WR is ≈50 minutes and it's a much easier playthrough, since you don't need to verify any of the tricky Number Cards along the way. Great practice for Any%.