Urgent Cybersecurity Breach Resolution Needed

A few days ago, I noticed a sensitive file on my desktop downloaded through my browser after I stepped away for a few minutes to grab a bite to eat. Upon reviewing the system logs I found someone with admin access to my PC had been making changes to my settings while I was not there. Upon further review, I realized than on that same PC there were 4 windows profiles I never created which stopped me from changing back certain settings. I checked add/remove programs and found virtual desktop software that I was unable to delete due to the elevated admin privileges of the hacker. I disconnected the Wi-Fi and checked the other devices in my home, and sure enough they were all suffering the same issue (profiles with admin access I never created). Also, upon pasting my router/modem logs into chat GPT, it told me there were multiple fishy things going on which indicate the network could possibly be compromised, so I'm assuming that the malware spread through the Wi-Fi. I've kept everything off WIFI, got a new modem from Xfinity, and purchased a new PC so that I could have something secure to use in the meantime for work, but upon setting up the Wi-Fi and completing Windows setup on the new PC, I noticed the same issue (multiple profiles with admin access I never created) directly after setup. I used a new Microsoft account which I created during Windows setup and took tried using every measure I knew possible to make sure the new router and PC were clean. I didn't want to use any devices I was actively using for setting up the new stuff, but I also didn't want to have to spend a bunch of money buying a new smartphone either. I tried resetting one of my iPhones, but even after turning off iCloud backup and Find My and doing a full reset, and signing out, the phone had backups and Find My on after logging in with my Apple ID. This persisted after 3 resets and contacting apple support for assistance leading me to believe the phone was toast. I ended up using a Samsung phone that's been powered off for years and got a prepaid sim so I could access the Xfinity app to setup the router. Assuming that this only happened recently, I didn't think to reset the phone which I probably should have. That said, the only way I can think that it possibly got reinfected is the fact I used this phone to setup the Wi-Fi, but I haven't used the phone since 2021. Does that mean that whoever did this hacked me all the way back in 2021 or even before, and the Samsung device was infected through compromised Wi-Fi back then, and reinfected my new modem which in turn reinfected the computer? If this has been happening for years and hackers have had remote access, collecting info to try to ransom me, steal my identity, or something worse, what are the next steps I should take? I've already filed an IC3 and taken steps to secure my most vulnerable accounts, but I'm at my wits end and feel like I need to contact a cyber security professional in my area to help me sort this out. I just can't find anyone online who has delt with this level of compromise to know I'll be getting my money's worth if I end up going that route, and I'm not well off enough to pay big money for this. --- TLDR: I got completely pwned, PC's, Phones, WIFI all ratted. What should I do to get at least the Wi-Fi, one phone, and one PC secured without buying anything new or spending more hours on the phone trying to get help from xfinity, verizon, and apple? How do I protect my family and I from identity theft, or ransom before they do anything? Is this a targeted attack specifically towards me? Given the level of compromise, should I assume the hard drives and possibly other components are toast on my PC's? Is it possible to find out who did this? Could this be the work of some kind intelligence agency? (P.S I'm not a criminal) Could this have happened as a result of the recent zero-day exploit on apple computers with intel chips on outdated software? (I have one). --- Any and all feedback is appreciated. Thank you in advance.