I have a long string of group SMS/MMS messages on my Google Pixel 3 How can I back them up to a computer?

My wife and I run a small real estate business. In the course of our business we often setup a group text between ourselves and the tenants so that everyone is on the same page regarding anything related to the rental unit. Long story short, I need to capture the entire group text chain stored on my pixel 3 and get it a computer so we can submit the entire chain to our attorney. Of course I could screenshot 6 months of texts 1 at a time, but there just HAS to be a better more efficient way. I have access to computers running Windows and Linux as well as an IPad. It would be ideal if I could get this info into my gmail account. Any ideas? Unfortunately testing indicates the suggested duplicate doesn't appear to apply to MMS..