I have one of the older Ryobi (5-3/8” I believe) 18V One+ cordless circular saws and it has worked well for me the past 13 years. If memory serves, it will handle up to 1-5/8” depth so it handles 2x4s well so long as the cut is not angled. Ryobi also has larger cordless circular saws as well, including a model that accepts full size blades.
The Ryobi tools tend to serve typical homeowner/hobbyist use quite well and deliver many years of service under typical use, though they are by no means professional grade and not intended for 8-hour a day heavy use which would wear them out far more quickly. For that sort of commercial use one would want to buy one of the more professionally oriented alternatives. But the serve more casual use very well and the larger batteries have a respectable amount of power and Ryobi has a very large lineup of compatible tools. I usually get around 5 years out of the Lithium batteries under moderate use (some last longer, occasionally one will fail soon, but 5 years is a generally safe average without fussing over battery state or conditions).