i cannot think how this is a good idea

you’re building a service on top of somebody else’s service, especially Google’s

as someone who built a SaaS on top of Google APIs, i’d be afraid to build another service that depends on them

Google will change and break their APIs more often than you’d expect, introduce new API versions and deprecate old ones without any backwards compatibility

you’ll be stuck in cat and mouse game fixing every damage introduced by changes in the API and your software will break completely when they decide to deprecate the API in favour of a new one

it’s only a matter of time until this product breaks because of Google’s API policies (remember there’s no warranty?) and your users/customers won’t keep up with that for long

advice for somebody who learned it the hard way: do not build a product that depends on Google, or you risk losing your business