I don't think it's the same as a custodial wallet because you're taking what is a non custodial wallet and for each additional client adding more risk by giving the client your node keys. This is the same issue as sharing nsecs with many clients and why nip07 was created for web clients. Maybe depending how the sdk is designed this could be mitigated. Where as a custodial wallet is fully custodial from the start.

Also with greenlight you still have to manage channels and liquidity it will likely have a higher balance then a custodial wallet where that can be handled for you.