I think Firefox + uBlock origin is a good shout. I personally would not bother with an antivirus; leave Microsoft Defender to it.

In terms of other software, it very much depends what it’s being used for. I’d probably put Sumatra PDF on there and make it the default (to prevent some of Edge’s shenanigans), LibreOffice (to ease opening random docs/xls, if you’ve not got Microsoft Office to install in your work), Notepad++ just because it’s quite good (and won’t have MS shitty AI unlike Notepad), VLC incase anyone needs it for basic media consumption, maybe a video conferencing tool if you use them (Zoom? Teams? Slack?), Paint.net as it’s a pretty good image tool for those random times you need to mess with images - way better than MS Paint and much easier for basic stuff than GIMP.

In terms of Windows settings, I’d google Win 11 privacy settings and follow the steps. It changes so often, but it is worth going into the settings and trying to limit the snooping and privacy problems as much as possible.

You should consider what Microsoft Account to link with the computer (if any) in case the laptop is stolen - both so you don’t have your own personal account on there but also so you can use tools like “Find my device” and lock the device remotely.

And if you don’t want to be tech supporting this, then honestly I wouldn’t donate this. It’ll always come back your way unfortunately.