That’s just a picture :)

I use Plasma 6 (and Arch, obviously).

Dunno, but these are just cheap paper stickers, although outdoor ones wouldn’t be much more expensive, I wanted to go the cheapest to see what I’ll get.

Local print shop. Here I chose A3 page “indoor matte” for €3.57. What I decide to do with that is on me. I put 88 Fediverse stickers on it, but if I wanted, it could have simply been 1 huge sticker.
“Outdoor matte” SRA3 (slightly larger than A3) would have been €5.29.

But processing is fully on you. You need to give them the printing template and cut templates. You also need to be careful about tolerances and spacings. Cutting tolerance is +/- 1.5mm, kiss-cut stickers need to have 5mm of spacing, die-cut 2-3cm, and they cost additional €1. Kiss-cut is thus most economical, and the result sticker is the same, you just get a large sheet rather than separate stickers, but you can just use scissors obviously.

I had to figure out how to do that in Inkscape.
Result:

I could have perhaps shifted them to fit a few more, but anyway.