I've thought about the same. I rely on Google too much. But "too much" is really only e-mail and cloud storage (Google Drive) for me. I only rely on cloud hosting for photos for a select few albums I intentionally want to share a link to, not as a full cloud of all my photos that I then rely on being there. I offload my phone and camera every now and then to local storage (NAS) at home, a hard drive in a safe deposit box at my bank, and then my Synology NAS runs an automated Backblaze backup which is very cost efficient for this use.

So I would only really need to switch

1) my mail provider to something else, which is easier today now that I rely on "messengers" more than mail, so not many people that I need to inform. Just subscriptions and account details that I can update one at a time.

2) cloud storage to something else, and there are oceans of alternatives there, many very capable.