Is there any app that is like discord or line but doesn’t require a phone number?
Try Telegram (you do insert a phone number, but it is not shown)
Do not look for Telegram.
Try Deltachat. It is chat via email)
Just download a spoof app and use that number. There are tons of free ones.
Being the majority of e&p players do use line or discord, I don’t see many using any other so could be a disadvantage to joining line groups. Discord I don’t have and prob won’t have unless I really have too.
I think with line your number is not seen anyway, iv had no issue using line pretty sure can block people too.
Why don´t create a forum for your alliance with a chat box? I know that it can look quite outdated, but it´s effective.
While not my personal choice, KiK fits the description you described.