Can I replace 均 with 都 here? Is this sentence still acceptable if I replace 均 with 都？ Or to put that another way, have I got the meaning of 均 here correct?

发达国家对产品生产等整个过程均需符合环保要求。

发达国家对产品生产等整个过程都需符合环保要求。
Yes, you are correct. In this context, both 均 and 都 mean all. 均 slightly indicates the variety of the processes.

均需 is formal and usually used in writing or lectures. 都要 would be one of the informal equivalents.