The term speedrun refers to completing the contract with a silent assassin rating in a time that is typically way below the average SA completion time. There aren’t any rules that relate to starting location, method of kill, and loadout. However, you can impose your own rules. For example, you might choose to do a SO/AO/!KO speedrun, which means you never change out of your suit (SO = suit only), you only kill targets with accidents (AO = accidents only), and you never subdue any NPCs (!KO = no-knockouts).
So it looks like you are planning to do a series of speedruns where the only (self-imposed) restriction is AO.
However, what do you do for the virus in Sapienza or Soders in Hokkaido? I don’t know what others think - and I don’t think there is a definite rule on this - but I would view the limitations of approaches by contract conditions. That is, you cannot mark either the virus or Soders as a target and regardless of how you “kill” them you will never lose your SA rating (as long as you’re not spotted). You could go to the extreme of detonating, say, a fire-extinguisher next to the body of Soders, but it will never register as accident anyway, so I think that those two targets would be a reasonable exception in your accident only campaign.
Let’s see what other players think.