If the “pa” part of “companion” comes from path

It doesn't though, it comes from French compagnon/compaignon and then Latin com (with) + panis (bread). It probably originally meant "someone with whom you share bread (eat together)".

And actually, looking at wiktionary, Old English had a word "ġefēra" (with the same meaning) which is constructed very similarly to "спутник": ge ('with', still the same prefix in german e.g. ‎Gebrüder) + fera ('to go'/'to fare', e.g. in seafaring)