My 10g is fully stocked and I love it. It has:
Fish:
1 tailspot blenny (perfect fish for a 10g, really--get a barnacle off of Etsy and it'll be super happy)
1 purple exquisite firefish (also good, but a bit more skittish--very impressive when it comes out)
Inverts:
4 rock flower nems (easy) + 2 sexy shrimp that hang out on the nems
1 spotted anemone porcelain crab that likes being target fed
1 green porcelain crab that also comes right up to me during feeding time
1 pom pom-less pom pom crab
1 lettuce nudibranch eating all the ulva it wants
Lots of different snails
1 crocea clam
Corals:
Hammer + octospawn island, next to a torch on the edge of the "mainland"
Zoas/palys/cloves on another island
1 rainbow favia
1 mint potato chip pavona
1 golden plume gorgonian
Macroalgae (highly recommended):
1 brotycladia (good medium-slow grower)
1 codium (prolific, can easy cut every two weeks)
1 pom pom gracilaria hayi (medium-fast grower)
1 galaxaura (most difficult, because nuisance algae like ulva or GHA grows on the branches and smothers it)
All of this fits and is doing well. I don't do frequent water changes anymore, only on an as needed basis so I don't bottom out NO3. Just adding ~2-3mL All-For-Reef every day to keep Alk and Ca up. A 10g is a great little tank for low maintenance and high visibility of your little guys!