It's not Torx it's a philips

My guess is a M2.5 screw which is a small Philips head screw standard like PH screws

I would recommend something like a Xiaomi electronics screw driver kit, fairly priced and has all the common screw drivers you need

https://www.amazon.com/Xiaomi-Precision-Screwdriver-Magnetic-Electronics/dp/B08MV2H7KD/ref=mp_s_a_1_7?dchild=1&keywords=xiaomi+screwdriver&qid=1611833975&sprefix=xiaomi+scre&sr=8-7