Production usage - small display (2.5"-4.5") .. can't find anything

I have been browsing alibaba and the web for quite a while without a solution so far.

I want to use the BBB and either Android or Linux (Debian) as core of a production project (thousands of pieces planned).

The main issue I am stuck right now is finding a small display 2.5-4.5 inches which can be connected and is supported by the linux kernel.
Almost all displays have one or another protocol which would have to be implemented.
Writing a kernel driver for a display is a big “no go” for me. Aside of possible problems and issues it’s just too much hassle.

So I was looking for HDMI displays but in this size there is nearly nothing available, HDMI starts at 7 inches.
I could find a few composite displays of that size, that however would suggest using the PI instead of the BBB.
I like the BBB way more and would like to go with it.

I am sure I have not been the only one with this problem.
Which small displays have been used ? I need a “lowcost” device that can easily be ordered in hundreds of pieces.
A (capacitive) touchscreen feature would be perfect but it’s not a must-have.

If a non HDMI display shall be used, is there something I could look for which is supported by the linux kernel ?

Help appreciated!