Photos filling up all storage on MacBook Pro, should i transfer to external hard drive?

I have 2 iphone12s and one MacBook Pro, all connected via iCloud. I also keep my photos on MacBookpro hard drive optimized for the thumbnails.

my macbookpro hard drive is filled up with photos so i can’t use the laptop at all, let alone update the software.

should i transfer all my MacBook Pro photos to an external hard drive (i bought a sandisk g-drive with 1 TB of storage at Apple Store)?

Would this affect my iCloud connection and therefor affect my two phones access to all my photos?

I want to keep access to my photos on my two i-cloud connected iPhones, I’m often sending old photos to friends.

now i understand that iCloud is a synching device. I don’t want to lose my many photos and i also want to keep access to them on my iPhones.

once the photos are on the external hard drive, are they still accessible via iCloud?

it also sounds like a lot of people are using google photos or Dropbox to store their old photos. Can i store on external drive and store on Google photos?

my goal is to be able to use my unusable MacBook Pro and also have access to my many photos on my two iPhones.

Thank you!