A group of scientists travels to a newly discovered planet shown to support life in the form of plants and animals. Obviously they can only bring so much food with them so at some point they would need to support their own dietary needs. Certainly they would bring along equipment for their research. I have seen other posts that reframe the problem as traveling to a different Era on earth, say a few million years ago, to replicate the problem more localy, and have seen some of the discussion on the potential incompatibility with alien protein. Depending on what you need to overlook the interstelar or Time travel element of this thought experiment and still treat the core of the question as rooted in hard science, the whole point is digestability of plant and animal material.
Is it possible to bring along something like spirulina to grow and sustain you over time? Is it plausible or even theoretically possible to sample the gut biome of local critters and come up with some kind of transplant that might overcome some of these issues?
For some clarity, the following posts talk about some of the issues around trying to sustain a group in a totally alien biome: