you can just open a channel with an LSP (its easy within their dashboad) using either lightning or on-chain...then send some lightning btc somewhere else (say like a coinos.io account or buy something somewher) to get some inbound liquidity. Now, any sub wallets you make will have their own accounting (starting at zero), and you can choose to top up with your own funds (this won't actually drain the node you just created, rather earmarks a balance in their sub-wallet..think fractional accounting at a trad bank but within your albyhub) or zap the wallet once the user is set up and it'll be added to their sub-wallet balance (this should work if you've created some inbound liquidity by sending some sats out of your albyhub). It'll work as it's own sub-wallet using the liquidity in the channel you opened with the LSP. Hopefully that provides clarity I really think it's the best option for what you want to do.

If you are going to be going this with other people using it, I'd recommend starting with at least 500k sats but please only do what you are comftorable with based on your experience and all.