I have two parrotlets. Think Amazon but tiny bodies and they don't know it. They can be territorial. They are like their cousins true Amazons. They love chewing like crazy. They are fun and adorable. They are pretty mellow since they are so little (compared to budgies) and basically believe they are the King and Queen of the whole room. Even Delphine my Lovebird doesn't stand a chance so I'm really really careful to never allow them to sleep together in the same cage.
My parrotlets eat fresh veggies every day. Mine love love kale, broccoli, cauliflower, sunflower seeds, millet and almost all fruit. I give fruit in the afternoon as they'll just eat fruit (lol as will my budgies). My mix is 40% roundybush crumble, 35% fresh dark greens (this includes sprouts every day), veggies and fruit, and the rest is seed and millet. I give nutriberries for the seeds but I'm positive they spit out the pellets. I also give Avicakes which they adore. I give mine some egg, fish, ground beef about once a week for protein per their avian vet for beaks, feet, nails and feathers.
Mine are bonded but I got Carmen first. Diablo and she bonded right away and they've been stuck together ever since. They will fight my dogs and you will be challenged as they act like big birds with tiny bodies. They are fun, adorable and very loving. I do not pet my parrotlets. I believe they would think that it's beneath them. I'm happy that they are happy and I'm not too handsy with them. They step up, down, kiss, and will come when I ask.
There are a few of us who have parrotlets on this forum. Everyone is a little different but with as much experience as you have, I'm sure you'll know what to do. Have fun!