Deal with the bigger immigration problem and have Trump steer away from just yammering away only about a physical wall to more of a comprehensive border solution that does include physical barriers and technology (which others have said the money would go to) and you'd have a deal in a second.
No, you wouldn’t. You are being faaaar too generous about what tightened border control Nancy’s open border zealots will accept. They will not accept any physical barriers even remotely resembling a wall. Maybe a chain link fence provided it does not exceed 6 feet in height and cannot withstand harbor freight-grade bolt cutters.
Conversely, pubs would gladly fork over fairly broad legal protections in exchange for significantly tighter border security.
For example, I’d happily grant blanket amnesty (except felons) in exchange for more physical barriers, more surveillance, more ice agents, more detention facilities and streamlined legal proceedings to end catch and release, statutory abolition of birthright citizenship (no, that isn’t “unconstitutional”) and mandatory E Verify.
Most of these are absolute non-starters for the left. Because they don’t truly want border security.