Baby food questions!!

Baby girl is almost 5 months, pediatrician recommended at 4 months we could start purées but we really haven’t started yet. I feel like she’s pretty much ready. She’s teething bad and I bought one of those mesh things you put fruit in. I read you can put frozen fruit in there to help teething. What fruit to y’all use ? Do you buy already frozen or do you buy fresh then freeze it yourself. Help! Please and thank you

Also veggie ideas! Can I put avocado in there? Sorry I’m a ftm lol! Do you make your own teething cookies? What is the best and most safe to buy?