There are still new S4 batteries manufactured by Samsung for Korean market, got mine in Poland for $25. I'm getting 5h+ SOT.
I'm not a performance-demanding smartphone user, but if I were, I would consider jailbreaking an iPhone. Android & Linux (Purism, Pinephone) keep disappointing me.
EDIT: maybe "disappointing" is not the right word. It's just that for good step, a step backwards seems to be taken somewhere else. Choosing a phone is all about trade-offs now, which is kinda sad. I'm using phone manufactured 6 years ago. Why can't I find any device that is a clearly improved version of it?