Disclaimer: Since we're from different countries (I'm from the US), I realize that I am necessarily speaking from a position of privilege. If I tell an employer here that I deleted my Facebook account, they'll usually understand because we're all seen the drama in our local news. Still, if you want to cut ties with Google/FB, I think it's best to start small.

Basically, you can start by coming up with a list of those Google/FB services that you use, and then figure out what alternatives (ideally open source, or self hosted) might be able to replace them. Don't feel pressured to do this all at once, just keep an eye out for alternatives and give them a try as time permits. The idea is not to keep all your eggs in one basket: what happens if Google decides one day to delete your account? You should ideally be able to brush that off and keep going.

If you're technically minded, a lot of those services can be self hosted on a cheap VPS. Granted means you're now trusting your VPS provider, but there are ways to mitigate much of that risk and since you're in greater control, it's easy to spread out. This is a good place to start:

https://github.com/Kickball/awesome-selfhosted

For email, I personally use a privacy-conscious provider, because I find self-hosting email is more complicated than I care to keep up with. I'm using Fastmail and have been pretty happy with them so far. It helps that they're not ad-supported, and their entire pitch is built on that trust, so I feel that they're a bit less likely to violate it; the PR backlash would ruin them. To each their own though.

And of course... some of the big services are genuinely useful! Even though I've reduced my reliance on Google, I still have that old account for the small handful of places where it's needed (rare) or where I personally find that it's the best choice on the market (Maps and Docs) which makes the risk worth it for some of my tasks. Just because I use their services sometimes though doesn't mean they're the only option; by this point I've got an alternative lined up for everything on my list.

Each task is independent, and each risk its own. Take the time, do the research, and learn to make your own informed decisions. You'll be glad you did.