Food suggestions for food feeders?

My little guy is coming up on 5 months soon and my husband and I have noticed him showing a ton of interest in our food lately. I know that babies can be introduced to solid foods between 4-6 months of age. We want to start out slow with him and opted to try one of those silicone food feeders. My question is... What is a good food to start with in the food feeder? What types of foods can even be used in those? I’m a FTM so any suggestions would be helpful!

Edit: Thanks for your opinions so far. I should clarify that we don’t plan on using this for actual feedings. We’ve already spoken with our pediatrician and are proceeding with her suggestions as well when it comes to starting solids officially. We’re more wondering if the silicone feeder would be helpful for helping our little one get a taste for things while relieving some teething pain. Our ped gave us the go ahead and actually suggested something like this to help with teething but she didn’t give much in the way of specifics. So I’m looking for suggestions of foods we could use in it for our 4-5 month old just to taste/suck on when teething. Thanks again!