Ensure that the WHERE clause used in the above query doesn't drastically change from your original query to fetch the product list, in order to avoid any additional pricebook IDs. Lets assume that the above query resulted in an array of the 6 unique pricebook IDs. You can use the code below to convert it into an object.

var priceBookIds = ['01s46000004XMWhAAO', '01se0000000sup8AAA', '01se0000000spgaAAA', '01se0000000spgkAAA', '01se0000000strOAAQ', '01se0000000sugVAAQ'];
var priceBookObject = {}; 
priceBookIds.forEach((element, index) => { 
    if(index === 0)
        Object.assign(priceBookObject, {'stpb': element});
    else
        Object.assign(priceBookObject, {['pb'+index] : element});
});

This above code would give you an object array as show in the screenshot below:

Now, you can update your JS code as shown in the sample below to make dynamic:

for(var j = 0;j < p.length;j++){
    for(var i = 0; i < p[j].length; i++){
        if(p[j][i].Pricebook2Id == priceBookObject.stpb){
            stpb.push(p[j][i].UnitPrice);
        }
        else if(p[j][i].Pricebook2Id == priceBookObject.pb1){
            pb1.push(p[j][i].UnitPrice);
            
        }
        else if(p[j][i].Pricebook2Id == priceBookObject.pb2){
            pb2.push(p[j][i].UnitPrice);
             
         }
        else if(p[j][i].Pricebook2Id == priceBookObject.pb3){
            pb3.push(p[j][i].UnitPrice);
            
         }
    }
    columnData.push({ 
        "ProductCode" : this.allProductColumns[j].fields.ProductCode.value,
        "Name" : this.allProductColumns[j].fields.Name.value, 
        "Family" : this.allProductColumns[j].fields.Family.value,
        [priceBookObject.stpb] : stpb[j],
        [priceBookObject.pb1] : pb1[j],
        [priceBookObject.pb2] : pb2[j],
        [priceBookObject.pb3] : pb3[j]
    });
}
this.allProductColumns=columnData;

Ensure that the WHERE clause used in the above query doesn't drastically change from your original query used to fetch the product list, in order to avoid any additional pricebook IDs. Lets call this array as priceBookIds and should as shown in the screenshot below:

Now, you can update your JS code based on the sample below to make it dynamic (note that I've retained the outer for loops as-is so it's easier to understand this code, but they can also be converted into functional constructs):

for(var j = 0;j < p.length;j++){
    // this object will be used to store all the pricebookId-Unitprice details for a given product
    var objPrice = {};
    
    for(var i = 0; i < p[j].length; i++){       
        priceBookIds.forEach(pbID => {
            if(p[j][i].Pricebook2Id == pbID ){
                // Here we are creating an object literal with pricebook ID as the key and the unit price as value in the second parameter using object literal notation
                // Append this new object literal to objPrice using assign method
                Object.assign(objPrice, {[pbID]: p[j][i].UnitPrice});                
            }
        });
    }
    
    // Using object.assign, append all the pricebook entries for a product to an empty object and push it into the data array
    columnData.push(Object.assign({}, { 
        "ProductCode" : this.allProductColumns[j].fields.ProductCode.value,
        "Name" : this.allProductColumns[j].fields.Name.value, 
        "Family" : this.allProductColumns[j].fields.Family.value}, objPrice)
    );
}