Ramp tests will give you A measure of MAP. But different testing protocols, i.e. the ramp duration and starting power, can result in different MAPs for the same VO2 max. The variation in MAP can be as much as 25%. Shorter ramps will result in a greater MAP than longer ramps (e.g. 30s vs 60s) The VO2 max, however, does not change.

There's a lot of science to this. If you want to learn more, Empirical Cycling covers it in many of their podcasts: https://www.empiricalcycling.com/podcast-episodes

A 20-min test may be a better barometer for FTP (many people, including the guys at Empirical Cycling, disagree with this.) The big problem with the 20-min test is that many people do not do it correctly. They fail to do the 1-min and 5-min all-out efforts to burn off anaerobic power before doing their 20-min test.