The Gemara in Eruvin 43a asks the following:
(Sources from Sefaria)
?בָּעֵי רַב חֲנַנְיָא: יֵשׁ תְּחוּמִין לְמַעְלָה מֵעֲשָׂרָה, אוֹ אֵין תְּחוּמִין לְמַעְלָה מֵעֲשָׂרָה
Rav Ḥananya raised a dilemma: Does the prohibition of Shabbat limits apply above ten handbreadths from the ground, or perhaps does the prohibition of Shabbat limits not apply above ten handbreadths? In other words, does the Shabbat limit apply only close to the ground, in which case walking more than ten handbreadths above the ground, would be permitted?
As one of the proofs that it does not apply above ten handbreadths the Gemara states the following:
תָּא שְׁמַע: הָנֵי שָׁב שְׁמַעְתָּא דְּאִיתְאַמְרָן בְּצַפְרָא בְּשַׁבְּתָא קַמֵּיהּ דְּרַב חִסְדָּא בְּסוּרָא, בַּהֲדֵי פַּנְיָא בְּשַׁבְּתָא קַמֵּיהּ דְּרָבָא בְּפוּמְבְּדִיתָא. The Gemara cites another proof: Come and hear a resolution from the incident involving the seven teachings that were first said on Shabbat morning before Rav Ḥisda in Sura and then repeated toward the conclusion of that Shabbat before Rava in Pumbedita, despite the fact that the distance between them is too great for someone to have traversed it on Shabbat.
The Gemara Rejects this proof citing that someone by the name of Yosef the Demon
מַאן אַמְרִינְהוּ? לָאו אֵלִיָּהוּ אַמְרִינְהוּ? אַלְמָא אֵין תְּחוּמִין לְמַעְלָה מֵעֲשָׂרָה! לָא, דִּלְמָא יוֹסֵף שֵׁידָא אַמְרִינְהוּ.
Who said those teachings, and delivered them from one place to the other? Was it not Elijah the Prophet, who traveled from Sura to Pumbedita by way of a miraculous leap through the air above ten handbreadths from the ground, who said them? Apparently, the prohibition of Shabbat limits does not apply above ten handbreadths, for Elijah would not have transgressed this prohibition. The Gemara rejects this argument: This is no proof; perhaps Yosef the demon, who does not observe Shabbat, reported these teachings and brought them from Sura to Pumbedita.
What I know so far
Are there any documented sources who explain who he is?