The team said in a Crowdcube update on 30 March that the campaign will run for an additional 14 days, or until it hits its £1m target, due to continued interest.
The riverside project in Bristol’s Finzel’s Reach development will feature a taproom, brewery and dining space.
Sanchez-Iglesias, who is behind the city's Michelin-starred Paco Tapas and Casamia, will run a development kitchen on the first floor of the site.
The space will have a small number of covers and focus on “experimental and innovative cooking” that will inform the menu at Casamia.
The chef will also create a separate menu for brewpub customers.
Left Handed Giant's campaign hit its initial £400,000 target within a day of going live and has so far raised £859,000 from 1246 investors.
The company, run by former BrewDog operations director Bruce Gray, has been brewing in Bristol since 2015.