You can share “bare” links by putting them in angle brackets:
<https://tiddlywiki.com>
I’ll have a look around the settings for not replacing with Title for TW links.
TiddlyWiki needs to implement OpenGraph tags to get extended embeds / previews. Unfortunately they only work per “real” page, so for TW you can have this just once for your entire wiki. This is because # routing is invisible to SEO and other requests.
More reading (with OpenGraph preview!):