Finally found one, Official PlayStation 2 USB mouse : r/gamecollecting
PS/2 port - Wikipedia
PS2-mus og tastatur for USB-omformer - DANBIT AS
Thanks to @El_Topo_54 advice I found a working mouse for my PS2. I tried Half Life 2 and Soldier of fortune :) . Any other games I should try with this? : r/ps2
Mus med PS2 tilkobling – elektron.no
KMU2P - USB K/M to PS/2 Converter - USB keyboard & mouse to control native PS/2