Apple - Is it possible to enable OSX keyboard text substitution in more apps?

The application needs to implement Auto Text Expansion and it hasn't been implemented in Chrome yet. You could try this Chrome plugin Auto Text Expander. You'll have to again add the text-expansions though.

Mac's Text expansion should work in Safari though. If not already enabled, you can enable by typing the following in terminal.

defaults write -g WebAutomaticTextReplacementEnabled -bool true

I gave up on TextExpander shortly after I started using it. It didn't work easily on iOS devices - although there is a compatible iOS app - and I just found it cumbersome to use. The updated version of the MacOS keyboard shortcut seems to work in more apps now and syncs across all of my Apple ecosystem devices.

I do use another solution for the Mac (this doesn't exist on iOS but it's excellent on the Mac) called "Clipy" for many items now that I'd otherwise have to remember keyboard shortcuts for. It's essentially a bottomless clipboard that allows personalization and organization. I recommend it for anything that you type repetitively but don't necessarily want to remember a shortcut for. Just invoke a keystroke to bring up the list of your stored snippets and pick one. Find it here: https://www.macupdate.com/app/mac/58124/clipy