Zen instead of Vivaldi, KeePass instead of Bitwarden
Aurora is just a frontend for Google play afaik so i don't know if it even counts. your best bet is fdroid obviously but in terms of apps available it's lackluster af and the UI looks like android gingerbread or something.
obsidian's cool but it's not keep-like at all. don't know what would be a good alternative off the top of my head but i bet there are tons.