Here is the full list of all 27 Ooblets achievements.
Sell 100 crafted items
Sell 50 crafted items
Fulfill 15 Plenny's orders
Collect 40 things from the sea dangler
Scan 25 ooblets at the Lernery
Travel to Tippy Top
Win 3 dance barn tournaments
Travel to Pantsabear Hill
Collect forageables from 4 different regions
Travel to Port Forward
Complete 20 Tinstle Tasks
Craft 20 items
Travel to Nullwhere
Complete 10 Tinstle Tasks
Travel to Mamoonia
Scan 10 ooblets at the Lernery
Get 10 friendship stickers
Win 15 dance battles
Harvest 50 crops
Get 3 friendship stickers
Complete 5 Tinstle Tasks
Get 150 friendship points
Look at 10 thingiedoodles
Win 5 dance battles
Scan 3 ooblets at the Lernery
Plant 15 seeds
Collect 60 forageables