can i use light side in archon normal speedrun ? of course i dont have a tactic in light side but i will find a way one day but im curious about light side ?

Yes, there is a "Player Force" option for each submission indicating which side you chose. Everyone has chosen the Dark side so far because it is believed to be faster, but anyone can choose the Light side.

I did some TAS work on the light side when I was strat hunting initially and never found anything fast enough to be competitive.

That said I am not infallible as a TAS author so I definitely encourage you to dig in and see what you can find!