No idea - maybe it depends on the manufacturer? That was the case with my current Nolte kitchen.
Assembling it yourself - well, maybe it depends on how straightforward the planning is. You’re not officially allowed to do the connections, it’s also an insurance issue.
I have to lay out the cards for myself if I really go to Ikea, everything will be in individual parts after all. It’s quite a big task to assemble it all.
The countertop is also a topic where I don’t even know if I would manage it.
I’m confident I can level the cabinets, but getting the gaps of all doors and drawers just right is definitely fiddly.