I've noticed a lot of product managers end up in a situation where an avalanche of shit is landing on their head from multiple sources.
When in this situation they often take it all on and view their job is to just keep shoveling - trying their best to dig themselves out - all the while failing to meet anyone's expectations and not having very much fun.
While this might seem admirable it is ultimately ineffective.
Part of the Product Management role is to clearly communicate to all stakeholders (including the people providing resources) how much is on your teams plate and if you need more resources, time and/or prioritisation.
The most powerful thing you can do is say "No" as clearly and thoughtfully as possible.
You do this in multiple ways, including...
1. Be ruthless about prioritizating your backlog (in collaboration with your stakeholders)
2. Provide clear information/visualization for your stakeholders about what's on your roadmap and how long things will take to get done.
3. Push back against stakeholders who say "Isn't it easy to..." or "Can't we just..." and instead make it very clear what it takes to build and ship a quality product (using your roadmap as a tool for communication).
4. Insist that if your team is going to be responsible and accountable for more than it can handle, that you either get more resources or fewer responsibilities.
If the stakeholders around you don't understand or respect this process, then you're also free to move on.