Which program is the one that surprised you most that it is available on Linux?
For me, it was perhaps simple-scan, a very simple and efficient GUI to scan documents. I used it with my Brother printer / scanner and it works like a charm. Especially since I do not scan stuff often, so a program with more complex UI would have the effect that I forget how to use it until the next time.
I convinced my work to let me use linux on their laptop. They sent me instructions for setup. One of them was to install Microsoft Defender, had a link to the Ubuntu package and everything. Blew my mind.
I don't know, but my guess is it might still be able to detect some cross-platform malware signs and detect malware intended for Windows on Linux machines (e.g. I can download a PDF or .docx that is harmless on my machine, but if I reupload and a Windows user downloads it, I've spread malware regardless). IIRC ClamAV is sometimes used to scan attachments on an email server, often looking for Windows exploits being sent through the server.
Wasn't too difficult as they already offered Linux as a supported option. But I had to justify it. I was already using a linux VM for all my actual work. So I complained about all the buggy behavior I had experienced. Didn't have to exagerate too much. I was properly modivated after IT sent out an email announcing the forced migration to Win11.