So this is typically where high net worth individuals (HNI) come in, aka, angels but not your typical tech angel and not seed funds IMO. I would argue a very large unreported, under discussed part of funding for traditional businesses is done this way, but it doesn't have the sex appeal of tech angels and VC's so people don't hear about it and the press doesn't cover it.
It is not rare to work with a HNI and they infuse you with say 50-500k for growth based on your business metrics. How they structure the deal can be very different, it can be anything from a "loan" with monthly payments starting usually after some number of months or it could be as ownership via shares or Units (for LLC's) and quarterly or annual distributions based upon an agreed to valuation. But there are almost an unlimited other numbers of ways this gets structured.
Not everyone is looking for 10x returns, a lot of HNIs will invest as sort of a paying it forward (they want people to succeed), but don't be misled they are still looking for solid returns. An example, I did one of these deals with an HNI where for every sale we made they took a percentage of the sale. Until the principle was paid back it was a higher percentage but it lowered once principle was paid back and the return was capped at a total value/time whichever occurred first e.g. they could get up to 4x their investment back or it stopped 5 years after the principle was repaid whichever came first, they were also guaranteed a specific return if we sold before either of the triggers happened. This deal worked for both of us, because as we succeeded they got paid and they were incentivized to help us succeed because they could get the max value out sooner the faster we grew.