The “Dr Berman’s Grid” shows which of the “Free money programs” are compatible with others:
Yes, it’s true that you can’t have PPP loan forgiveness and also use the Employee Retention Tax Credit.
The paid sick leave tax credit isn’t part of the Employee Retention Tax Credit, or even part of CARES thing, it’s a FFCRA thing. If you give emergency paid leave to employees, you may credit it against your payroll taxes, but you can’t use it as a PPP qualified reimbursable expense.