I honestly believe Trump would take a reasonable compromise.
Yup. Whatever else you can say about the guy, his whole shtick on this is the same as buying a piece of real estate - offer and counter-offer.
The dems are refusing the negotiations, and thinking about it more, they are really shooting themselves in the foot about it. Were they to sign off on the "downpayment", it could actually help them a few years down the road. The downpayment amount isn't enough to cover more than a few strategic areas. They've got a "gimme" for a few years down the road to say, "See! Walls don't work!" because people will still be getting through unsecured geographic gaps that need a barrier.
Also, the Trump admin is getting all the heat for "fed employees need food banks to survive" and Pelosi, et. al. somehow seem to be Teflon on that. Which is a bit hypocritical because they're the ones supposedly "standing up for the employees". If the employees are that important, then sign off on a couple of billion dollars (which many on the dem side are apparently okay with). It's a drop in the bucket of money spent on stuff like lobsters on treadmills.