If you hover your mouse over any links do they point to a genuine site or not?
If you change the password on those accounts & they stop then someone has been trying to hack the account.

I’m sorry for your loss.

If you have the backup codes then you can use one of those, failing that if you can obtain a replacement SIM card with the same number then you may be able to receive a one-time code via text, if there’s a recovery email on the account you could try sending the code to that address.
As a last resort you could contact support with the death certificate & see if they can help

If the card has a switch then ensure it is up/on position when formatting. If it is or it doesn’t have a switch then the card has failed & cannot be recovered.

I would download an adblocker &/or use an Adblock extension like Ghostery, AdGuard, Adblock Plus etc.

Is the pop up onscreen no matter whether the browser is open or closed? Is there any X to close it? If you can close it does it return?

Have you cleaned up all your browsers But the problem persists?
Can you provide a screenshot?

Was this via a browser? It sounds like one of those ‘your computer/device has a virus’ pop up scams Which ask you to call a number to remove the ‘virus’.

You should backup your favourites (if possible) then close Edge/browser, either by clicking on the X, by ctrl, alt del & then open task manager & find Edge/other browser entry & click on this & choose end task.
Then open Edge/other browser & it will offer to start afresh, you can then clean the browser’s cache, cookies & history.
If this isn’t enough you can reset Edge by Right-click on the Start button in the lower-left corner and select “Apps and Features “.
Scroll through the list until you find “Microsoft Edge”, click it, and then click on the “Advanced options” link.
Next, click on the “Reset” button.
For other browsers then they also may have a reset feature, if not then you can uninstall & reinstall the browser.

Is there a new Touchpad entry under Settings>Devices? Are there any of those settings there?
The newer Elan/Synaptics driver seems to break the touchpad settings so that you cannot turn the touchpad on/off or use various scroll options.
Try installing the Microsoft precision touchpad driver:
https://www.tech-recipes.com/rx/66163/how-to-install-precision-touchpad-drivers-on-windows-10/ This will add extra touchpad options under Settings>Devices>Touchpad.

I suspect you’ll need the original sim or a sim from the network the phone is locked to then you can request the unlock code, enter this with the original sim inserted then it will unlock.