I don't know if this is allowed but you can try to see if anyone is interested in doing this but I doubt it because they could just use a vpn or something like this even if they were banned from a site to be able to place their bet.
It is allowed but I'm quite sure no one will take this service since there are many ways people can get accounts to bet by themselves instead of going through with the third person.
In short, I can get sports bets on for those that are unable too ( before anyone trolls there are many many people that are un-able to place bets due to account closures , restrictions and I guess location
To provide this kind of service first you need to be a well-trusted member of this forum then members can trust you and send money first otherwise not possible run this kind service. I will not send money online to any who is not trusted.