You can use two Electrum mobile to do that and phones with working camera (Only download Electrum from:
https://electrum.org/#download).
One offline phone containing the seed and another one with just the master public key that can't be hacked.
Please, do you have any article for this?
I'll edit this post / reply with the steps since I haven't found a tutorial for electrum mobile in the internet.
This is so informational, thanks so much. So far you talk about the phone camera, it means I can make use of QR code to easy complete the transactions by using the cold mobile device for signing. It is a lot better than using USB stick.