Are you suggesting that there's no need for Redis to integrate persistent-storage support because every user should download some library and patch the Redis source themselves? And that would somehow be better?
I'm suggesting you haven't read enough before replying, just like I did on my first comment. See "Myrocks" as an example of what the first user meant with lmdb. Replace "mysql -> redis" and "rocksdb -> lmdb".
I'm looking for a standard, well-known, drop-in product - that's what Redis is, that's why persistent storage support in Redis is interesting. If I have to search up some combination thing then it's already a non-starter.