Truss in Scissor Lift

yes, why not

Trusses do not work in Tension so you need more than just a truss

Compression they don't work in Compression

No.

Truss analysis assumes no torque is applied at each node, thus members are in compression or tension only.

The rigid members making up a scissors lift are loaded in bending. The "frames" that make up a scissor lift are 4 sided, which is unstable and requires more contstraint to remain rigid.

The scissor lift arms are more like beams. u may consider the free body diagram and find out the loads at every hinge point and then take it as a beam in bending with the max stress at the center pin. take the requisite factor of safety