On my desktop computer that runs Linux, and where I mostly type code and write in English, I use US English as the input and a Dvorak-based layout in hardware that I made for my programmable keyboard.
Since I very rarely type in my native tongue on that computer, and I annoyingly frequently have had to reinstall the OS from scratch, I no longer bother with customizing xmodmap or similar things on that computer.
So the few times when I have to type æ, ø or å on that computer, I just Google aelig, oslash or aring respectively and I go to the Wikipedia article about the letter or some other page from the results that has the letter on it and copy it from there.
Works well enough given how rarely I type any of those letters on that computer.
Since I very rarely type in my native tongue on that computer, and I annoyingly frequently have had to reinstall the OS from scratch, I no longer bother with customizing xmodmap or similar things on that computer.
So the few times when I have to type æ, ø or å on that computer, I just Google aelig, oslash or aring respectively and I go to the Wikipedia article about the letter or some other page from the results that has the letter on it and copy it from there.
Works well enough given how rarely I type any of those letters on that computer.