Yes, you can use jowar idli mix as a substitute for rice idli mix to make a healthier version of idlis. Jowar is a type of grain that is high in protei,fiber and othet macro & micro nutrients and is considered to be a healthier alternative to rice in some cases. It is also naturally gluten-free, which can be beneficial for those with gluten sensitivities.
However, it is important to keep in mind that jowar idlis may have a slightly different texture and flavor than rice idlis, as jowar is a different grain. Ultimately, the decision to use jowar idli mix instead of rice idli mix will depend on personal preference and dietary needs.