can we direct traffic based on IP address

I'd use an address-based data group, two pools, and a small iRule. Example:

when CLIENT_ACCEPTED {
    if { [class match [IP::client_addr] equals my_ip_dg] } {
        pool srv1_pool
    } else {
        pool srv2_pool
    }
}

where "my_ip_dg" (arbitrary name) is an address-based data group that contains single (client source) IP addresses and/or subnets. Also, using two separate pools allows you to add additional resources later if you ever need to scale out the application.

For sure, you can check IP address on client side, and select a member on server side.

https://devcentral.f5.com/articles/irules-101-05-selecting-pools-pool-members-and-nodes.UksHqmRRlRQ

https://devcentral.f5.com/wiki/irules.ip__addr.ashx

Hope this help. Let me know if you do not find your syntax in the irule 😉

Small i.e with pool selection :

when CLIENT_ACCEPTED {
if { [IP::addr [IP::client_addr] equals 10.10.10.10] } {
pool my_pool
}
}

You might be better off using two separate Virtual Servers and the Priority Group Activation feature but if you really must have an iRule;

when CLIENT_ACCEPTED {
 If the source IP address is in the internal network;
 if { [IP::addr [IP::remote_addr] equals x.x.x.x/xx] } {
    continue and check if both Pool members are up
    if { [active_members pool_name] > 1 } {
        if so, select our prefered pool member for internal traffic;
        pool pool_name member x.x.x.x
    }
    else {
        if not, exit and let the standard load balancing method do it's thing
        return
    }
 If not an internal, assume it's an external IP and check if both Pool members are up
 elseif { [active_members pool_name] > 1 } {
        If so, select our prefered pool member for external traffic;
        pool pool_name member x.x.x.x
    }
    else {
        if not, exit and let the standard load balancing method do it's thing
        return
    }
 }
}