Looking for Free Api's for Address Auto Completion and Geocoding

I am working on a flutter application for both ios and android using Flutter Flow. I am working on a feature where users can search for listings in a specific area(Requires Address) or nearby(Using Mobile GPS).

I am looking for any api's or libraries which can help me achieve any or all of the following. At the moment I can't invest money into using Google Maps Api's or any other's that involve money.

1. Help users with suggestions as user types in the address into a search box.
2. Once an address is selected from suggestions, Convert the specific address to Latitude and Longitude.
3. OR Show a static map to user and allow user to place a marker on the map which can return coordinates and I can use them to list nearby listings.

Can anyone suggest any api's or services I can use for the above use cases? I know there's always a price associated with such huge implementations. But looking for suggestions from community and combine them into workable solution.

Thanks in advance.

Looked at Google maps Apis, Open Cage api's.