SQLite does support auto-incrementing: https://www.sqlite.org/autoinc.html. Is your gripe with the lack of "GENERATED BY DEFAULT AS IDENTITY" syntax specifically?
Yes, sorry. My gripe is that we don't have a single general way to say "I don't really care about the specifics, I just want a number that goes roughly upward" for all database engines. SQLite is interesting in that it supports at least two distinct sets of semantics for auto-incrementing rows, but neither of them are the standard syntax...