Sure they turn yellow. This is my Meyer. I think the fruit would taste good even if not quite yellow though. Just give them time.

My Meyers always turn yellow on the tree and can stay that way for weeks until I pick them. Meyers have one of the longest time on the branch of any citrus. Just like it takes humans nine months to make a baby, it takes Meyers about nine months per fruit. Just be patient.

My Meyers turn from green to yellow to orange. When they give a little when squeezed that's when they are ripe. When the nights start to get cold is what helps them get orange... I think.

This photo was of part of this year's crop:

I agree with Kate, I think the color change is at least partially colder temperatures. I overwinter all the citrus in a chilly garage and note the color changes in autumn and winter. You might not get this under warmer winter conditions.

My Meyer lemons are grown 100% indoors, with the lowest temperature of the year reaching 65.5° F and they all turn a delicious golden yellow every time

Thank you! I will try to be patient a little longer. It was -30 C here this morning but sunny and the citrus trees sure are a happy reminder of warmer days to come 😊

Those photos are gorgeous too - just a little jealous of the lush leaves and fruit!