I recently dealt with this myself. We talked to our contractor about adding double cylinder locks to some doors. We have some french doors, and the manufacturer didn't want to talk about adding a second cylinder, to lock them from the inside.

We have added some simple barrel bolts to one door, the least secure one.

No matter how many and how good your locks are, you cannot keep someone who is determined from getting in. You can only slow them down. I think the best contributor to the security of our home is our neighborhood. Some of that is from the homeowners' association and paid for, but a lot of it is the neighbors watching out for each other.

If you have layers of security then defeating each layer takes time and effort, all of which gives you time to respond or get assistance in doing so.