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