Replicators already covered everything we’ve seen of programmable matter, except for the tether which would have been covered in the past by some sort of higher power more focused tractor beam. If anything, DIS programmable matter doesn’t go far enough.
In the book Superluminal they have grist which is programmable matter, but it is also computing material (you can just have buckets of the stuff running simulations or what ever), it is versatile enough to create solar system spanning structure which can flex and stretch to impossible degrees to follow planets as they orbit, it can be a glass substitute used on bottles but which is unbreakable, and it can be eaten as food.
So far, DIS programmable matter has only made one ship critical device, has been used for some repairs to a station’s systems, has bonded the Discovery’s nacelles to the hull as a backup, presumably created Burnham’s emergency vacuum helmet, created a tactile data output (which could have been done holographically), and a tether.
I still cannot tell if the phasers are programmable matter or self replication, because the transformation isn’t distinct enough but looks a little like shuttle replication in Prodigy. It does not look like the helmet creation nor dusty effect of the tether or web like emergency nacelle attachment.
We’re talking about a setting which had sentient nanites 700 years prior as a common enough tech a boy genius got his hands on them for personal experiments. And those sentient nanites were given a planet, and presumably recognition as people. It’s also a setting where Borg nanoprobes act like replicators, reconfiguring materials they are injected into, as seen in Enterprise.
Programmable matter’s limitations are rather surprising given what older technologies could do. All we’ve really seen is an ability for the material to configure itself into shapes with non-mechanical functions, but not necessarily anything a replicator couldn’t. We haven’t seen it used as a computing medium, unless the killer wall at the end of season 3 is just that. We haven’t had a comment about it changing material properties (hard, soft, more or less dense, more or less conductive, magnetic, etc), which is a hallmark of programmable matter. It just seems to be reconfigurable, and possible self propelled given it can swarm.