I've read somewhere that Telegram exports work this way, you get a bunch of raw files somehow organised with directories and browsable by themselves, with a tiny local static website to browse them more conveniently.
So different from the last such mass export I used: Google Takeout, which produces a dumb dump of cryptic xml and raw files named in some nonsensical (to the user) scheme. To this day I'm not even sure I got all the data I asked for before deleting it cloudside.
HTML ready sucks for archiving.