The 17-year-old, born in Guinea-Bissau but a resident of Spain since the age of six, has been a revelation at Camp Nou this season during an inconsistent first half of the season from Ernesto Valverde's side.
Fati was cleared to play for his adopted country in October and was named in the Under-21 squad for this month's qualifying matches for the Euro Under-21 finals in 2021.
Moreno admits he will keep an eye on the winger's progress with a view to including him for the senior tournament next year, for which Spain have already qualified.
"Ansu Fati is in the preliminary list and so there is no reason why he can't be with us at Euro 2020. He ticks all the boxes," Moreno told reporters in Madrid.
"Dani Olmo enjoyed a great tournament with the Under-21s [at this year's European Championship] and he's doing well for his club in the Champions League. We're very happy to be able to give him this opportunity," said Moreno.
"Gabriel Paulista is processing his passport but right now he cannot be called up," he said. "When he gets his Spanish passport, we'll see.
"There are a lot of very good players but only 23 are able to make the squad. Out of a list of 45 players, we end up selecting the 23 who we think will do the best."
Moreno took charge after Luis Enrique stepped down in June for family reasons.
The 42-year-old wants to remain at the helm as far as the 2022 World Cup, but he says there are no plans for talks over a new deal.
"I haven't been offered the chance to renew and nor am I expecting it to happen in the near future," he said. "If you were to ask me how long do I expect to be in the job - I would like to still be here for the Euros and the World Cup - so at least for one whole period. But that will depend on the results, that's how it is for all coaches.