How can you generate 10m keys?

If you already have them then you can use Electrum but the problem is I think the Electrum will hang if you paste them all.
So you will need to separate them no tools yet to import such a huge amount of private keys.

I search a bit that you could import them through bitcoin-cli on Linux so you will need bitcoin core for this and it should be fully synced to be able to see balances of those wallets.


If you don't have those keys yet it's impossible to find an address with balances it seems you are looking for a brute force tool that generates unlimited private keys and automatically checks balance.
Never heard of a tool like that but you can develop it on python.