I'm from Southern Germany.
And yes, I do tour with it. The longest was about 800km in a week through the Black Forest. It's important to remember that every fixed gear bike has three gears: sitting, standing and walking.
But I also noticed that when I start to walk on a steep hill, my riding partner with 30 gears usually follows soon after.

I admit I wasn't smiling on some of those miles.

It's only bad for your knees if your gear ratio is too big, you try to push up too steep hills, or if you ride brakeless.
On tour I ride with a 39/17 ratio and two brakes, and when it's too steep, I walk.
I do bring a spare freewheel cog with 18 teeth to limp home when I'm absolutely done, but I haven't needed it yet.

You wouldn't wanna see how smug I can look, when other riders arrive at the top of the highest hill around with their E-MTBs and notice my bike, while I'm sitting next to it drinking beer.

I'm a bit obsessed with steel frames, horizontal top tubes and single speed.
Which limits the options for bikes somewhat.

The only good reason to ride fixed gear is if you enjoy riding fixed gear.
It isn't objectively better in any way.
But it gives me 10x more smiles per mile.
The fact that I can pull it out of the shed after a year, pump up the tires, and start riding is just a bonus.

https://hilosports.de/products/fahrrad-hinterradtasche-wasserdicht-25l-doppel-set
Hilo Sports is a small and pretty new Austrian brand.
The bags are cheaper than Ortlieb, have similar features, less durability and less weight.