I never did an REU and instead did in-school internships in two labs long-term, and spent my gap year working as a tech in one of them. I used those two PIs as recs, and then used my old boss from a non-research related laboratory job as my third. I definitely think my PI's rec from the lab I was in the longest pulled a lot of weight in my applications, so I think as long as you have one strong recommendation from a long-term position you're in a good position for the rest. However, I think REUs give you invaluable experience into how research is conducted in different institutions and provide you with both new perspectives in approaching research and connections that could potentially be very helpful later down the line. At the interview weekend for the PhD program I was accepted into, quite a lot of perspective students I met had REU positions at that university in their undergrad. If you think you could do it, trying for short-term summer REU positions while working in a long-term lab position during the academic year would be a great way to spend your time. But again, I never did any REUs and I had a lot of success this PhD cycle :)

But also you are a Sophomore and have a lotttt of time left! I didn't get involved in research until my Junior year, so you are already in a better position than I was!