o/
So let's start with easiest one – Survival. While it's total RNG where you spawn from, I guess it's still acceptable to have any% category with whatever rules (PvE/PvP, rush DZ, craft rocket, call extraction, kill hunter, leave). We also could add cache% category – extract with 6 Survival caches – so one would have to kill DZ boses (which would enforce different route to farm better gear or #yolo). Current WR seems to be 09:46 for any% by IamChappie (, control gained at 00:09, control lost at 09:55).
Underground is total RNG, yet there could be like simple% with 1-step, no mods, normal mission and hard% with 3-step, all mods, heroic (or is it legendary) mission. Don't really know what's best here.
Resistance. Maybe wave-15%? You have to kill first hunter bosses on that wave. This would provide enough challenge and set exact goal to reach. Also Resistance has least RNG of mentioned game modes, as you are able to control where NPCs spawn by positioning yourself (basically not total RNG).
Looking forward to your ideas here.
Survival, sure as people already 'speedrun' it (as you said, there's already a record). I've been tempted to try this myself but I'm quite slow with survival, not because I'm bad, but because I like to loot way too much. Underground is ehh because no one really speedruns it anyways so no real point in going very in depth with it. I think some people did in 1.7 but I'm pretty sure that was a one-off. Resistance is a no from me. "Speedrunning" a wave survival scenario is imo a dumb idea. Might just be me though really.