Importing photos from iPhone to MacBook - how do I know which are missing?

I'm using a MacBook Air (2018) running macOS Sonoma and an iPhone 6 running iOS 15.

My iPhone has 32gb and is full. I would like to transfer all of my photos from my iPhone to my MacBook to free-up space. I tried to do this by connecting my iPhone to my MacBook and using the import function of Photos on my MacBook, but it didn't find all of my photos. I searched online and found that my iPhone will have uploaded full-sized versions of some of my photos to iCloud to save space. I turned off 'optimise phone storage' and tried again, but the Photos app on my MacBook still didn't find all photos. I tried turning 'iCloud Photos' off, but a warning message popped up saying:

This iPhone was not able to download 1,798 full-resolution photos and videos. If you continue, the low-resolution versions of these photos and videos will be removed.

I don't want low resolution versions so I was going to click to go ahead, but then I realised that these 1,798 photos can't download because there isn't enough space on my phone. I thought I could go ahead and import the photos that are on my iPhone onto my MacBook, then delete those from my phone to allow the other 1,798 to download - but I realised I have no way of knowing which photos on my phone I could safely delete as I can't tell which 1,798 are only thumbnails.

I'd just like to get my photos onto my MacBook. iCloud has confused things. I don't want to sync my MacBook and iPhone - I have tried this previously, but because I share my MacBook with my partner, I couldn't find a way of syncing without getting confused with her photos.

Can anyone help?