Are certifications popular in Japan, are they highly rated?
There are many cloud DevOps certification on the market today from AWS, Azure and Google.
These are very popular in the SRE fields.
Can these help or count towards work experience for a visa with you are just shy of the full 10 years?
My main experience is with startups, who I don’t think value certificates particularly. More traditional companies may value them, and certainly there are Japanese engineers obtaining them though.
Most likely they would not count towards to the 10 years of experience for getting an Engineering visa without a degree.