I am a pure user. I am using both TiddlyWiki and Obsidian now.
(I use Obsidian more than 1 year. And I start to use TiddlyWiki last month.)
Obsidian has two offical feature about graph, that is Graph View and Canvas.
And a lot of great graph plugins, for example Excalidraw.
About Obsidian Graph View (using graph to display connection between notes), just like @arunnbabu81 says.
About Obsidian Canvas (this is more like tranditional mind-map), TiddlyWiki has plugin TW-whiteboard.
I think TiddlyMap is more powerful than Obsidian Graph (since it can create custom linking), but it’s manipulation way is also more complecated (need more time to learn). By the way, Obsidian Graph and Echarts is prettier in my opinion.
But the key point is that Obsidian has Canvas, Canvas is really powerful (since it can quick search user notes to add in graph, add pure custom text cards, add custom tag on link, add any media in library, add external link, even more embed external link like video so that we can watch video in Obsidian, and it can use all color by color-picker, etc…). And this is why I can’t complete switch from obsidian to Tiddlywiki since Tiddlywiki can’t really make a tanditional mind-map.
P.s. I really love TiddlyWiki, but when I using TiddlyWiki, I feel it loss some features for create tanditional mind-map, even use TiddlyMap + TW-whiteboard + Echarts + Mermaid. Since every note in TiddlyMap is tiddler. But sometimes I prefer to use a pure text node (Just like the cards in Obsidian Canvas). Although, we can use TW-whiteboard to draw a simple tanditional mind-map, but it reallt need more features (take a look at Obsidian Canvas). And for Echarts and Mermaid, they all need to write codes (need lots time to learn😂).