What I have done to get balanced channels is I will open a channel with another node using my umbrel, then send funds from that channel to an external custodial lightning wallet I own. Once my umbrel channel is half outbound and half inbound I then send the funds from the custodial wallet to my strike account, and then send these funds back to my umbrel with an on chain transaction. Then rinse and repeat until I have several balanced lightning channels I control. It's a pain in the ass but it works.