Probably shouldn't tell border patrol you're doing unpaid labor in a country you're visiting. When speaking to authorities it's best to say the absolute minimum required for the encounter.
Europe treats tourists from developing countries way worse than US does when you apply even for short term tours with all details. US looks at bigger picture, history if any, financial conditions but Europe literally wants you to have planned down everything to the most relevant detail and will then issue a visa 1 or 2 days longer than the itinerary and ask you to piss off