I am using Baseus 65w, 26800 mAh battery with MyVolts step up and it works flawlessly if someone is wondering.
Baseus can output 12v trough usb-c and usb-a (orange color) ports.
Powering DT2
USB-C, even better. Thanks for the link
thanks for the first hand suggestion. Iām checking prices and models in this very moment:)
Baseus battery and MyVolts cable both have readouts, so you can know voltage used, battery percentage etc.
Also in Europe we have limitation up to 30k mAh battery, so this one can go into plane and hand luggage
Shortly after this conversation, and after quite a few thoughts, I decided to go with the solution Iām sharing below. Maybe sooner or later it could be useful for someone to know that it has been working smoothly for me for many months now.
In the end, I decided to get a 25k mAh power brick from Ugreen, which, as Kokosnuss also suggested, allows me to travel with it while complying with European restrictions. For me it was also important to be able to plug in, besides the DTII, a laptop as well.
As for the cable, I wanted as few adapters as possible, so the ideal solution for me turned out to be the Ripcord from Step Up rather than the 12V Tip.
Thanks again to everyone in the group for all the replies and support 
