IBM would make more sense than Google. Despite the topic of TFA, almost all of GitLab's ARR comes from their on-prem offering not their SaaS offering. IBM is much better positioned to sell and support on-prem software than Google. IBM is also a long-time player in SCM, and despite being legacy their Rational products still have a big footprint in enterprise. With some integrations and migration tools an IBM-owned GitLab would have a huge installed base to go sell Git modernization to.

Another possibility would be Broadcom, as CA has a number of adjacent products for the software development lifecycle.