Comment by CamouflagedKiwi

I've done this before, using Google's semi-standard ByteStream messages. It works, but is a bit of work, and I really don't love how you're building on top of a protocol that completely solves streaming contents of arbitrary size, which gRPC drops, and you have to reinvent again in the application layer.

I know it's not easy to solve given how protobuf-centric it is, but this is the worst piece of gRPC for me. The 4MB limit is a terrible size, it's big enough to rarely hit in test cases but small enough it can hit you in production. If you control it all you can just lift that number to something arbitrarily big to avoid most things just failing (although you probably don't want to use that as an actual solution for streaming files of any size), but in practice a lot of "serious" setups end up contorting themselves remarkably to try to avoid that limit.