Hello,
On ISG devices, you unet vsd 0. Create multiple VSDs in such a way that some are active of one node while other are active on another node.
On SRX devices, when you create a reth interface, you bind it to RG group. You can create multiple RGs and depending upon its priority it will be active on different nodes. This is a basic desing though which utilizes data plane active active behavior.
Regards,
Rushi