Yeah for completely new users that's an issue. But if you have no other way to get sats, maybe just use a KYC method to get some sats, like Strike.
You don't need a lot. Say you wanted to buy $100 worth of BTC on Robosats. The default fidelity bond is 2% of that, so you only need $2 for the fidelity bond.
Then once you have that $100 worth of sats, you have enough of a fidelity bond for whatever size purchase you want to make on Robosats, because the purchase size currently maxes out at at $3280.