Has anyone used Adobe Express (or Canva) to help non-designer colleagues to create on-brand deliverables more easily? What's that experience been like?

I agree with Anthony Ugo and the others below -- it can be a great time save when supported by strong design guidelines and appropriate human supervision. "Real training" on Canva is key -- go slow at the start to go fast later. Finally, even with strong brand guidelines, design is highly subjective, so things can fit the technical guidelines, but still can not be on point, so emphasizes the need for human review as mentioned above.

Tools like Adobe Express and Canva can be game changers for non-designers. In my experience, they work best when paired with a clear set of brand templates and guidelines. Colleagues can quickly produce visuals that feel on-brand without needing deep design skills, which saves time and keeps messaging consistent. The key is balancing freedom and structure: give people creative flexibility, but provide pre-approved colors, fonts, and layouts so outputs still feel professional. Overall, it’s a great way to empower teams while maintaining brand integrity.

Yes, we've just begun utilizing Adobe Express templates (created by our in-house designer) and they have been very well received.  The key is identifying the templates most needed, as now the asks for new ones has expanded. 

Yes, my team uses Canva for social media graphics, email header designs, and any creative needs for the TA org. We've been able to upload the required fonts and colors into the brand style guide so everyone on the team has access. Canva is highly user-friendly, and we can easily share links with our corporate brand team for approval on designs before using them externally. 

Yes – both are great tools to help broaden ability to create branded collateral. Top tip would be to have your brand owner/designer input a full brand style guide into the tooling in advance of sharing access. Think of it as them providing you the tool kit so you are not starting from scratch, rather working with the right pieces so all you have to focus on is content. This shortcuts the onboarding time and when followed ensures compliance with brand standards. Bonus support for them to provide a library of editable templates (ex: one pagers, social media) that help streamline the layout of content. 
When I have shared this for non-designer colleagues I find a quick walk through session is best to get them thinking about how to look at existing material and leverage the toolbox to create what they need. 
Also would encourage Youtube as a first line of defense when questions/challenges arise, there are a lot of great tutorials for beginners for both platforms. Also doesn't hurt to watch a video or two on basic design theory, like visual hierarchy.