The OLS problem can also be viewed as minization problem. Here is an example to solve it with proc optmodel.

%let n=10000;

data t1;
   do i=1 to &n;
      x=rannor(123);
      y=1+1*x+rannor(123);
      x0=1;
      output;
    end;
    keep y x x0;
run;

proc reg data=t1;
model y=x;
run;
quit;

proc optmodel;
   set I = 1 .. &n;
   number y{I};
   number x{I};
   number x0{I};
   read data t1 into [_n_] y x x0;
   var b0, b1;
   min f =
      sum{k in I}
         ( y[k] - (b0*x0[k] + b1*x[k]))**2;

reset printlevel=2;
   solve with nlp;
         
   solve with qp;
   print f b0 b1;
quit;