AD&D like a lot of D&D editions was all over the place on the defific status of things like archdevils and demon lords.
2e Planescape Planes of Law says it is not known whether the Lords of the Nine are powers or not, but also that "The known Lords are called on by insignificant primes to the point where it gets to be a bother."
2e Monster Mythology lists a few specific demon lords as full patron deities to specific monster races. Demogorgon for Ixitxachitl, Kostchie for frost giants, Baphomet for Minotaurs, Juiblex for aboleths, Sessinek for Lizard Kings, Lolth for drow, and Yeenoghu for gnolls. It does not list any of the Lords of the Nine as specific patron deities.
In
1e Greyhawk the setting specified for the Horned Society that "Deviltry is the religion of the Society, and its leading Hierarch is purported to be an evil high priest of 18th level." In 2e they were overthrown by Iuz so they do not have a lot of detail. The
2e City of Greyhawk has a hierarch of the Horned Society in one of its adventure sheets as a 14th level priest with full spells, "Here, Vazirian the Hierarch is busying himself with some last-minute proofreading of a new Unholy Text of Asmodeus."
The late
2e Guide to Hell said that of the Lords of the Nine only Asmodeus was a full god, the others were special cases, beings who controlled a planar layer but were not powers and had no mortal followers. Asmodeus also predated the needs of belief for powers and is said to have no followers in this product.
In 1e the D series of modules there are plenty of clerics of Lolth, and she is clearly referred to as a demoness and not referred to as a god while Blibdoolpoolp and the Elder Elemental god are referred to as gods. It is not until Q1 and the Fiend Folio that she is specified as both a demon lord and a lesser goddess.
In
1e Deities and Demigods it said that the archdevils from the MM "should be treated as lesser gods, though they very rarely have human worshipers" It says the same thing for Lolth from the Fiend Folio and gives her a full deity entry.
In the later
1e Manual of the Planes it said "The arch-devils are a group of powerful devils (treat as lesser gods in their home plane)"
2e Forgotten Realms Powers & Pantheons has the demigod Gargauth, reportedly an outcast former Lord of the Nine.
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