This is the best information I’ve found on the airport strikes: https://www.portugalresident.com/new-airport-strikes-loom-for-portugal/
I, too, am traveling to Portugal during this time frame.
From what I understand, your experience will depend on your flight itineraries. If upon arrival in one of the affected airports, first having already gone through passport control at another European city in a Schengen country (like Paris, Madrid, or Amsterdam), getting through your arriving Portuguese airport should be fairly easy. You’ll only have to go through customs, with nothing to declare.
If, however, you are flying into one of the affected airports without connecting at another Schengen airport first, you’ll have to go through passport control at one of the Portuguese airports, which is where it gets sticky. You can expect long delays.
Flying out of Portugal is a similar scenario. If you’re not connecting elsewhere in an airport in a Schengen country, you’ll likely encounter long delays at the airport, especially if it’s Lisbon.
Now, you know about as much as I do. 😕