Do you make this addon also for other platforms? I assume this one is only for the raspberry?
Yes, this one is only for RPi. The idea is to put this addon into libreelec repository for everyone who needs it without requiring special image with everything included.
I need to make few more tests before that. If you need addon for some other platform let me know.
Schorschi79, if you can try this addon I just made. I made only few tests and seems to be working.
Install addons manually
service.system.tslib-8.0.100.100-RPi-arm.zip
or
service.system.tslib-8.0.100.100-RPi2-arm.zip
and Estouchy skin
kodi-theme-Estouchy-17.0-beta1-81d5d26.zip
Then you need to configure it like described in LibreELEC
follow steps in 7.1 regarding ts_env.sh file. The only change is that path is not
/storage/.config/ts
but /storage/.kodi/userdata/addon_data/service.system.tslib. Skip autostart and calibration part. Just reboot and under addons look for calibration addon and calibrate screen. Immediately after calibration touch should work and you can switch to Estouchy skin.
I only have two special LVDS displays which works out of the box on Udoo imx6 board. I don't have any HDMI screen with USB touch but I know they work well when configured properly. The biggest I know of is 40" display on RPi used in museum used by visitors 
UPDATE: rearranged few things and now I have service.system.touchscreen addon.
Final question, if nobody can answer or do not want to, can anyone tell me how to install LibreELEC on the USB hard drive? That way I can at least eliminate the extra USB flash drive. I can't find any information on the forums or Internet on how to to this.
It's not about not want to answer. Sometimes there are just no answer possible. I can't fix problems I can't reproduce. I can't even fix problems I can reproduce if they are some deep imx6 related stuff. This platform just newer got much attention from devs (there are only few who has knowledge about it - and I'm not one of them). I wish I could make perfect 100% working image but I think this will newer happen. I think 7.0.2 was very close to that (for some).
And about installing to USB: You still need SD card to boot from. The procedure is the same as for RPi (boot from sd card, system from usb).
Currently all this extra touchscreen stuff is build as part of the image. I did rewrote some parts and transform this functionality into addon. Will take few days to test and then I will give you the addon.
I'm using Ubuntu 14.04.5 LTS but v16 is fine too (64 bit of course).
Great. Thanks for reporting back.
I mean I have to to make addon from this. Let me try in next days.
Can you try this version: LibreELEC.USB-SD.Creator.Linux-64bit.bin
There has been one bug regarding mmc devices which should be fixed.
Yes, you get something but at the same time you lose something 
I think the best approach would be to transform this functionality into proper addon. Then it could be installed from repository to get same functionality on all images. Will think of that.
Schorschi79, you need to be more explicit: which image did you use before and which are you using now?
This will be hard to crack.
Can you run app with --debug parameter and put result on pastebin.com? Start without sd card and then insert it when program already runs.
Can you also show me the partitions on this card? sudo fdisk -l /dev/sdX
And can you wipe sd card with sudo dd if=/dev/zero of=/dev/sdX bs=1M count=10 and then attaching it when program runs.
And can you try using this sd card with USB reader to see who is doing this problems (sd crd or reader).
And if you want I can build one special build for you with mode debug messages in. If you are interested...
Install addon from ZIP: kodi-theme-Estouchy-17.0-beta1-81d5d26.zip
I don't know about including in by default.
Kodi beta3 version: kodi-theme-Estouchy-17.0-beta3-7041777.zip
ls: /storage/.config/firmware/: No such file or directory
mkdir /storage/.config/firmware/
You could copied this file to /storage/.config/firmware/ without squashing.
It it possible to update to a newer version without loose my configuration and driver?
Save folder
/storage/.config/ts
- there are touchscreen related configuration files.
But you must update with a version which actually includes all this touchscreen stuff. Meaning not official image.
There is no need to format because we write complete disk image to a USB stick/SD card. Any data on a device is overwritten.
But you can use SDFormatter tool to remove both partitions and create only one big one when you don't need this device for libreelec.
You missed the fact that official images doesn't include all what is described in this thread. You need special image build by yourself or some other good guy. Ask in thread for a new image.
I don't think there was any changes in this area. Which touchscreen is this?
Evtest addon should be available as part of system-tools addon.
The question was about why Libreelec removed it?
Because libreelec extracts skin from kodi sources and use only Estuary.