Maybe they can work on writing content marketing articles or documentation, link building, partner outreach, building relationships with potential customers, mapping out growth strategies, handling social media, looking for key opinion leaders, getting key facts that demonstrate your value prop, figuring out good questions for sales scripts, listing requirements for contracts and T&Cs, doing the bookkeeping, looking for subsidies/funding, getting a feel for what competitors are doing and probably a million other things that we as solo founders have to do.

Good luck