Suggested APIs are just that, suggested. Feel free to find others.
Bonus points for using geolocation for detect my location.
Resources: https://openweathermap.org/api, https://darksky.net/dev, https://www.i18next.com/
Create a simple Jeopardy style website with categories of topics
Resources: http://jservice.io/
Create a searchable card generator with categories for spells, monsters, loot, weapons, etc...
Resources: http://www.dnd5eapi.co/
Create a searchable card generator with for all the Pokemans
Resources: https://pokeapi.co/
Create a searchable cocktail database
Resources: https://www.thecocktaildb.com/api.php
Create a bitcoin dashboard showing the current price index of Bitcoin and other crypto currencies
Resources: https://www.coindesk.com/coindesk-api, https://api.coinpaprika.com/v1/coins/btc-bitcoin
Create a searchable job postings website
Resources: https://jobs.github.com/positions.json?description=api
Create a website that fetches data about the IP address you give it
Resources: https://ipinfo.io/161.185.160.93/geo
Resources: http://makeup-api.herokuapp.com/
Use geolocation to detect the closest breweries near me.
Resources: https://api.openbrewerydb.org/breweries
Resources: https://randomuser.me/api/
Create a searchable super hero database and link related heroes/villains
Resources: https://superheroapi.com/, https://developer.marvel.com/
Create a searchable Hearthstone database
Resources: https://hearthstoneapi.com/
Resources: https://dev.npr.org/api/
Create a ton of cool things with the NASA API
Resources: https://api.nasa.gov/
Bust the bad guys
Resources: https://github.com/fbi-cde/crime-data-frontend
Resources: https://geekflare.com/flight-data-api/
Resources: https://www.yelp.com/developers/
Do sports stuff
Resources: https://rapidapi.com/blog/best-sports-apis-ranked/
Create a Netflix or Hulu clone
Resources: https://www.themoviedb.org/documentation/api
Resources: https://covid-api.com/, https://leafletjs.com/
Make a dice roller app where the user can select all manner of dice to roll (and multiples of, too).
Resources: https://developer.spotify.com/documentation/web-api/
Create a dashboard showing launch pad data and upcoming events
Resources: https://github.com/r-spacex/SpaceX-API
Create a video game deals website that can allow user the create a profile and save notifications on titles, genres or price points.
Resources: https://apidocs.cheapshark.com/
Make a mobile app called Peddlr (or something spunky). "Hey Peddlr, I need a bike. ::ring:: Ok, here are the bikes I've found."
Return the results. If you can make it voice enabled then you get ⭐ ⭐ ⭐ ⭐ ⭐.
Resources: http://api.citybik.es/v2/
Chuck Norris joke generator. FYI, there is an 'explicit' category for the NSFW concerned.
Resources: https://api.chucknorris.io
Make a random numbers website where users can put in a year and get trivia returned to them about that year (maybe a in the year you were born trivia).
You could also create a simple React component that is really just a loader that shows random math trivia while the user waits for something. Resources: http://numbersapi.com
Make a searchable movie database. Resources: http://www.omdbapi.com/
Make a random joke generator or make a Hello Dolly Wordpress plugin, but make it a Joke of the Day WP plugin.
Resources: https://jokes.one/api/joke/, https://official-joke-api.appspot.com/