So, you want something that is equivalent to paid Canva. Not just free Canva.
I suppose that would depend on how you use Canva.
I use it for rapid iterating. I haven't found anything that matches Canva for that. If you just need an editor then there are a variety of alternatives, like Inkscape.
I only found it necessary to pay for Canva once I needed to upload fonts.
Id say Inkscape and Penpot are the closest but none of these (by design) include a big template gallery which is maybe part of your consideration.
On the template gallery you could use an open source chat-gpt like tool to create svgs for you and then load them into the above. Eg “Make an SVG of a smiley face”
The biggest selling point with Canva is it's myriad of templates. I doubt you're going to find that in a open-source alternative.
For drawing arrows, I use drawing toolbar of LibreOffice Writer.
For vector graphics, and converting bitmap to vectors, I use Inkscape.
For flowcharts, I use Dia.
For bitmap graphics, I use Gimp, use it for crop and prettifying old photos.
I use OpenClipart SVG images, when I need some image that is already made.
I am always looking non-subscription options for similar..
playing with affinty designer, similar.. eyeing luminero neo?
Appreciating self hosting AI gen..
Microsoft Designer is really making me happy - but I worry they will subscription paywall it eventually - I would pay a one time fee.
Someone has to have list non-subscription alternatives to all the things.. like photoshop alternatives you can own..
Not sure about open source, but there are alternatives out there:
Not necessarily like Canva, but more similar to Figma is Penpot, if it may interest you:
https://penpot.app/