@whale-av $100 might get you something in the low end Electribe range, but that is pushing it and there does not seem to be a market for low end small manufacture music gear, the big names have that area pretty well tied up, small manufacture is mid range and top of the line. $20k is not much when it is split between 5 or 6 people, which is about the number of people you would need to do such a project in a reasonable amount of time assuming these people enjoy having a life. If that is still too steep there are plenty of ways to trade labor for cost when starting out. Final assembly, installation of thru-hole parts, moving from board mount to panel mount for pots/switches/etc, off the shelf box with custom panels. Some companies have started out with a sort of kit, buyer does final assembly, which generally is just mounting the board, closing up the box and pushing on the knobs, see a fair amount of this in the eurorack world and even Korg has gone down this path. Lots of options.
An aside for touch screens, they dislike wet fingers and that is fairly important to remember here, fine in the studio but not so great on a hot sweaty stage. Products aimed at live performance should have all performance controls as physical controls. This is probably the main reason as to why touch screens have not replaced physical controls and most often serve primarily as a screen which also happens to give easier access to the deeper editing functions.
Also related to the protection of the work, is there any solution to make the project "closed" ?
Not really, and making it closed would kill most if not all of the advantages of going the linux/pd route.