Ok, I answered my own question as I am stubborn and won't give up on this.
This is a known issue (
https://github.com/spesmilo/electrum/issues/3302)
So basically if using legacy addresses, no development is planned, but using native segwit, offline signing WORKS.

SomberNight commented on Apr 6
(updated: 2018-05-10)
Recap:
Trezor:
legacy does not work, no plan to implement support
✔segwit works
KeepKey:
legacy does not work, no plan to implement support
segwit: keepkey itself does not support segwit
Ledger:
legacy does not work, no plan to implement support
✔segwit works
Digital Bitbox:
✔legacy works (because dbb does not want previous transactions)
✔segwit works