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