As far as I know everyone is still working off screen captures - no exhibition photos, publicity photos, no interviews with the costumers to indicate a paint manufacturer. I haven’t yet even seen anyone attempt this costume.
Personally I’d wait until some more research material comes available; print photos, behind the scenes footage that shows paint on a workbench, maybe reach out to prop / costume crew for a lead on a paint line... until then I’d start by experimenting with spray paints and model paints.
This is where the ESB & ROTJ Fett community was years ago, before the age of blueprints and templates and paint codes. To get there for the new Mandalorian Fett, it’ll take time and people are going to have to put paint to plastic and post their results
