Why is this significant?

because it uses all 26 letters of the alphabet

@ninalanyon Intriguing question! There probably are, though like that and Glossy's example, likely only as word-puzzles.

It led me to think of a more common aspect of at least the English language: letter-doubling, starting with those six:

E, O, R, T, also B, C, D, F, N, M, P, S.

I think aardvark and vacuum are the only examples of twinned 'A' and 'U' - and the former is from the animal's own country.

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Welsh of course uses 'DD' (pron. TH), 'FF' (spoken as the English single 'F', given a 'V' sound in Welsh) and 'LL' (pron. something like THL - very hard to represent fairly in a text-message. So twins acting as single consonants.

Not always easy for non-Welsh speakers, especially in combinations as in Rheilffordd Ffestiniog (Ffestiniog Railway), Ystradfellte (a village near Merthyr Tydfil) or Ogof Ffynnon Ddu which I gather is the 'Cave of the Black Spring', also in S. Wales.

Whether Welsh has an equivalent to Tumbleweed's and Glossy's canine and bibulous English examples, I have no idea, but would it treat dd, ff and ll as being as different from d, f and l, as say, ø is from o in Norwegian?

All the letters of the English alphabet. But what I always wonder is this: is there a version that has fewer repeated letters? E, H, O, R, T, and U are repeated. And also are there similar sentences in other languages and are they actually used?

...because you misplaced "brown" in the classic sentence which uses all letters in the English language as a typing exercise.

The quick brown fox jumps over the lazy dog.

yet another attempt to divide wild and domestic canines, breeding hatred and discrimination by spewing the same tired stereotypes, bias, unsupported facts, and blatant lies. It's a dog eat dog world 🤷‍♂...except in some parts of Ohio 🤔

This is more significant - - - The quick fox jumps over a lazy brown dog.

You now have only 1 "the" word (exchanged for the word "a") which also means you don't need as many letters.

Here’s a shorter one.

Pack my box with five dozen liquor jugs.

It's a test for all the letters on a keyboard (previously typewriter) isn't it?

It’s code to activate a sleeper cell