I think the key question is to ask what about Googles solution is driving them to look elsewhere. Once that’s known it’s possible to work out if NextCloud deployed in house or via a partner is the right way forward, or if another cloud offering might be more suitable.
For me it’s a HomeAssistant instance. Great product that has some very tangible use cases that can benefit ones household in terms of being able to implement nice automations etc, and also a great hub in that it supports such a broad range of products and services. As an Apple user in particular its one of the great ways to get non HomeKit certified devices working with Siri/Homekit on my other Apple products.
It also makes installing addons a breeze including other products people have mentioned here such as AdGuard Home (as a PiHole alternative) and the like.
A few years ago I’d say it wasn’t for the average Joe, but I think the product has really matured and is much simpler than it used to be. There’s a strong community out there too.
For multimedia I’d say Plex personally, but Jellyfin would be another option. Good way to manage personal media libraries.