I vote we bring back “aether” as a valid term. The aether is stretching everywhere, and in so doing it spreads distant things away faster than light can overcome.

I mean that's just space

When I read this, it seems to me like this is more or less the same as saying that the speed of light is decreasing, but I am probably wrong?

Is this something anybody ever thought out to look at things this way? Sounds like an intriguing Gedankenexperiment

Yeah, ideas like this are usually called "tired light" models, they have been extensively explored for the last hundred years or so. A lot of these models have been shown to be false by experiments, but I guess if you try you can probably cook up models which haven't been falsified by anything yet.

Like if you calculated the speed not in meters per second but fraction-of-the-universe per second?

What if space isn't expanding and we are just shrinking?

only if the expansion is really equal everywhere I guess