There are quite a few Delphi open source projects on GitHub that can really save you some time. I searched for Delphi on GitHub and then sorted by the Most Starred projects and came up with this Top 10 list. There is some really good stuff here including Awesome Delphi (which is another top list), Delphi IDE color theming projects, an MVC web framework, a REST API client, Open Source Computer Vision Library headers for Delphi, a really powerful custom TreeView component, a unit testing framework, a component for embedding Chrome in your app, and finally the fantastic OmniThreadLibrary.

Open-source seamless access components for Raspberry Pi breakouts.

Feature overview
The TMS LCL HW Pack for Raspberry Pi contains components that offer seamless access to various breakouts.

Components for viewing, navigating, text extracting and editing PDF files.
uses PDFium open-source PDF rendering engine
available for .NET 2 - 4.7
source code included in registered version
royalty free distribution in applications

Communication protocols 3964 and 3964R for .NET.
available for .NET 2 - 4.7
source code included in registered version
royalty free distribution

.NET NFC library for Android.
uses Android NFC API
provides reading, writing and formatting NFC tags
supports NDEF, NFC-A, NFC-V, MIFARE Classic and MIFARE Ultralight tags
source code included in registered version
royalty free distribution in applications

Use OCR.NET component to retrieve text from image, for example from scanned paper document.

uses Tesseract OCR engine and Leptonica image processing library
available for .NET 2 - 4.7
source code included in registered version
royalty free distribution in applications

uses ZBar bar code reader library
supports EAN-13/UPC-A, EAN-8, UPC-E, Code 39, Code 93, Code 128, Codabar, PDF417, GS1 DataBar, GS1 DataBar Expanded, Interleaved 2 of 5 and QR Code barcodes
available for .NET 2 - 4.7
source code included in registered version
royalty free distribution in applications

Add Gantt chart and scheduling capabilities to your .NET WPF application. ActiveGanttCSW can be used with practically any development environment and .NET language (VB.NET, managed C++, etc.) that supports WPF development. Use ActiveGanttCSW to build Gantt Charts, rosters, equipment/location rental, TV/Movie scheduling, and many other applications.

TVideoGrabber is a video capture/media player SDK for development of C#, VB, C++, Delphi, C++Builder, and ActiveX-compatible applications. TVideoGrabber captures and records video and audio streams from video capture devices supplied with a DirectShow driver like USB webcams, USB analog capture devices, HD PCI cards, desktop, as well as from set of bitmaps used as video source.