Phoenix at the first replenishment of the balance opens the channel. It is advisable to open a channel immediately for a large amount, since a fee of 3000 sat is charged for opening a channel. And if the liquidity is not large enough, then it may happen that the channels will be opened more often and for each opening of a new channel, you will again have to pay 3,000 sat.
You can top up on-chain (it’s a little expensive now) or from another LN wallet.
This is a very good solution, and non-custodial.