For your bucket, I completely agree.How about a proximity / level indicator?
A two part device, one in the cab and the other on the bucket.
Unless you are on perfectly level ground the level indicator itself won't be of any use.
But knowing the angle of the bucket in correlation to the angle of the machine would be useful.
A level bucket on a 10° slope is useless.
Note that as a merchant, I would raise no objections to someone who wants a second one for the cab as you suggest. Maybe a bundle with a 2" for the cab and a 3" one for the bucket? Then you match the bucket one to the one in the cab if you're on a slope.
Of course, it depends on what you're doing on that 10° slope. if you're going down it with something on your forks, best to keep the forks level relative to gravity, not the slope.
<sigh> There's probably an instruction sheet in my future.