Yes, you can use Squirrly SEO alongside SEO plugins in compatibility mode. You can learn more about how to use Squirrly SEO in compatibility mode here.
If Squirrly stops handling source code changes, then it works with RankMath, SEOpress, SEO Pressor, AIO SEO, Yoast, and others.
Basically, you can use Squirrly SEO to power up WP on top of everything that is already handled by the other SEO plugin you are using.
Of course, you can also decide to switch to Squirrly, as it offers the complete SEO funnel. Check out these graphics to see how Squirrly compares to other SEO plugins such as Yoast, RankMath, SEOPress, and All in One SEO.