We have a huge sand bur problem. Bad enough I said we will not get another dog until we get the burs under control(we lost our sweet boy in 2020). I have tried everything labeled as pet safe for years as we have free range chickens and an outdoor cat. Nothing works. This year we went nuclear and did Prowl H2o at its strongest labeled concentration. Praying it works, but I really can't tell you yet if it has. The burs are my archenemy and I hate using poison, but nothing else worked for me. I spent hours daily digging them up and bagging them, spraying 30% vinegar, etc.
I kept my chickens and cat in for a few days while we sprayed and watered in the poison.
I wish I had better advice, but after fighting them for 5 years and they just got worse every year, I threw in the towel.