I've a Windows PC and a Google account and my friend have an iPhone and an iCloud account. How can I share a bunch of photos with him?

I've a Windows PC and a Google account and my friend have an iPhone and an iCloud account. How can I share a bunch of photos with him? - 1

Yes

If your pc supports it bluetooth, or maybe connect a USB cable to your pc and transfer it that way

Email them or put them in a Dropbox account.

You can give him the address of your Google Account and let him access it to look at the pictures or you can email them to him. I do assume that you are talking about having the pictures in Google Photos. I just have mine all marked as public and that way anyone can look at them or download them.

You would be given URL for public access of your photo album. I forgot the exact step but Google has it and I've done that for Microsoft OneDrive and sure Google has it too.