The best way to play this game as a free to play is to create multiple accounts, i believe as many as 3 would do the trick. My point is, if you just care about the characters, tying the out and such but you just cant afford how insane the game pricing is, well, just use 3 accounts, roll each banner with only one of them, save up on the others, when next banner comes up, roll with one of the others, i feel like 3 banners is usually what it takes to get a 5star, of course it has only 50% chance of being the banner on but its better than nothing.
Grinding accounts isnt really that bad, given how little content genshin has to offer lategame, i found it rather refreshing actually.
Following this method you can at least ensure a shot at getting each banner without having to skip rent lol, and remember that if you miss the 50% chance to banner 5 star, you are guaranteed to get the banner 5 star next time, even it might be a different banner.
Im sure this sounds tedious but once you have accounts leveled its just playing for dailies and resin. 30 mins at most to all 3 combined.
Play with 3 accounts, roll with one and save up on the other two, then put that one away and start saving up while rolling with another one, so on and so forth, keep rotaring accounts and with a bit of prepararion you can roll on each banner for a chance to get the char!
edit1: people are a bit mean but i think they failt to understand how different each account feels, i’ll talk my experience, one account was my first one, i got specialy unlucky with character rolls, got just weapons, i reached ar40 with about half of the 4 star chars only. On my second account i rolled a mona early, got to try her out, i also got a constelation 4 benett, got to experience what that is, its pretty fun, and on my third account, i rolled not only a razor, which i dont have in none of the two accs prior, i also got a const 4 fishl, something that again, i coudnt have gotten in my main acc.
I got pretty different experiences with the accounts, i get this is not the solution we want but its the solution i offer besides spending 400 usd to get ganyu.