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