Professional and short brand name that plays both on the word "up" and "app".
The name "uppso" has only five characters and only two syllables. Two-syllable names are extremely rare and highly valued. Established brands using two syllable names include Google, Buffer and Subway.
Uppso.com is a .com domain. Dot com is the most desirable domain extension. Once you own a .com, it will be much easier to rank for your own name in Google.