Have experienced (not on the level you are describing!) but similar things. I have a friend who is a great hacker, 20 years of experience. He targeted me.
You need to buy new hardware, change everything out at the same time. Router, PC, phone, TV, etc.
What helped me was to put that friend in a separate user profile with end session option (we use briar to communicate). He cannot access other profiles, only the one we are communicating in. He sends links/pictures/PDFs embedded with malware.
Another solution is to get 2 sets of everything.
1 online PC - 1 offline PC.
1 online phone - 1 offline phone.
Etc
And change emails, phone number, and so on. Otherwise the hackers can keep sending new malware to old accounts, zero-days are uncommon - but they do exist.
If you dont know who is targeting you, its hard to know what measures should be taken. Stay off windows is a starter, qubes or immutable linux is better.