Generally, it is much easier to find tools for more widespread architectures, such as x86. Still, there are plenty of options available to analyze samples that have been built for other instruction sets. As a rule of thumb, always check whether you can get the same sample compiled for the architecture you have more experience with. This way, you can save lots of time and provide a higher quality report.
All basic tools, such as file type detectors, as well as data carving tools, will more than likely process samples associated with most of the architectures that currently exist. ODA (Online DisAssembler) supports multiple architectures, so it shouldn't be a problem for it either. In addition, powerful frameworks such as IDA, Ghidra, and radare2 will also handle the static analysis part in most cases, regardless of the host architecture. If the engineer has access to the physical RISC machine to run the corresponding sample, it is always...