In my head I feel like I say "ess-cue-lite" pretty much every time.
I see the point of the later if you are prone to verbalize acronyms:
SQL => Verbalized Acronym: "See-Quell" vs Structured Query Language: "Ess-Queue-Ell"
So then See-Cue-lite is a concatenation of the verbalization with the "lite". Whereas Ess-Cue-Lite is a concatenation of the acronym pronunciation with the "lite".
This probably solve the former question of why some people say both and don't understand why. If the conversation/person is saying "SeeQuel" and "Sass" or "less" etc. then "See-Cue-Lite" fits that dialect. In a dialog with a lot of acronyms e.g. SQS, VPN, AWS, etc. you are probably more likely to go the acronym route i.e. "Ess-Cue-Lite".
The term itself is a bastardization of an acronym and the "lite" term, I'd argue there's no correct pronunciation.
And when you apply FUSE (or FUSE-T or NFS or WebDAV) to its archive format "sqlar", getting a file system called "sqlarfs", then pronounce it as "sclarfs", rhyming with snarfs/scarfs/barfs.
Reading up on the history parts in the Wikipedia article, the German language version presents it as if SQL was the Oracle (Relational Software Inc) implementation of IBM's Sequel, the English page says the name was shortened due to trademark issues, before mentioning any implementation outside IBM. That would make Sequel and SQL the same thing, just rebranded early on. It also lists a clever (b)acronym and two other reasons for why they called it sequel before shortening, so it seems like there's a decent amount of mystery around the name. Almost as if it happened before the invention of writing.