I found several different approaches for a magnetic tube coupling system, which all have their pros and cons. However, I was not fully satisfied with all of them especially, as most of them only relied on friction to hold the ptfe tube.
In my approach, I use ptfe clamps which are also used in e.g. V6 bowden hotends.
Here is the link to the clips I've used:
https://a.aliexpress.com/_EJ5SexA
For the couplers, you'll also need 10x4x5mm magnets (10 mm outer diameter, 4mm inner diameter, 5mm thickness). Make sure to get the orientation right on all the parts ;)
For the blindplug, I used M4 washers with the size 4.3x20x0.9mm and inserted them with a pause in the print.
I recommend using 2.5x4mm ptfe tubing from ptfetubeshop
The author remixed this model.
Included ptfe clips for improved tube mounting