Hi debating,
Any type of foam (polyfoam, memory foam, latex foam) comes in a wide range of firmness levels and can be either softer or firmer than wool depending on the specifics of the material and on the specifics of the wool topper you are comparing it to. There is more about wool toppers in post #8 here and the posts it links to.
Every layer and component in a mattress or “sleeping system” will affect the feel and performance of every other layer and component above and below it and the mattress “as a whole” so the only way to know for certain whether any combination of materials or components will be a good “match” for you in terms of “comfort”, firmness, and PPP will be based on your own careful testing or your own personal experience.
The actual firmness of a particular layer or component is only one of several specs that makes one material feel softer or firmer or more or less pressure relieving than another (see post #4 here) but in very general terms thicker layers of the same material in the same firmness level will feel softer than a thinner layer of the same material and will isolate you more from the firmness of the layers underneath it. There is more about the effect of thickness in post #14 here.
“Support” is often misunderstood because the goal of a “supportive” mattress is to keep the spine and joints in good alignment and this requires the type of contouring support that allows some parts of the body to sink in more (softer) and some parts of the body to sink in less (firmer) and this will vary on an individual basis. There is more about primary or “deep” support and secondary or “surface” support and their relationship to firmness and pressure relief and the “roles” of different layers in a mattress in post #2 here and in post #4 here that may also be helpful in clarifying the difference between “support/alignment” and “comfort/pressure relief” and “feel” and how they interact together.
Phoenix