I know BB & Altera (archer) can be acquired through rare prism shop, but I’d rather spend 10+ RPs on something else (and I dun even have 5 RPs on hand atm)
The earliest welfare I was able to get was Yu Lancer since I joined JP ~8/2020. I know there were Irisviel & other AoE welfares who fare well in battles, but personally I kinda got the hots for only ST welfares (except for Nightingale Archer whose offensive AoE NP & skillset are pretty handy)