My philosophy on this is that PMMs should almost be embedded into their counterpart Product/Engineering teams. Schedule or scope changes shouldn't come to them as a surprise.
We have utilized multiple tools like shared calendars, regular update meetings, dependency tracking tools, etc. Those are all useful but they are just tools. The intent is for PMMs to constantly stay in touch with the Product team to understand the what, why, and when of the customer value being delivered. Having this mindset and being an active participant in decision-making builds empathy within PMMs for the realities of Product delivery and empathy within partner teams for the downstream dependency pressures that PMMs feel for Product GTM.