reader mode on iOS Chrome?
Someone suggested I use Workflow to address another question I had.
And it occurred to me that I could use it here as well (you'll need to be at least on iOS 11.x - Workflow is much, much, less powerful on 10.x.
You need to create an Action Extension workflow, set it up to only accept URLs and then choose Open in Safari as an action.
You may also need to enable Workflow in sharing.
configuration screenshots
Here's a rough series of screenshots, from when you've launched Workflow.  Sorry, it's a little bit complicated and fully detailing each step in the series would take a lot of little dialog screenshots, but hopefully you'll get the idea.
Also, keep in mind iOS 12 is apparently replacing Workflow with Shortcuts so there might be another way to do this later.
Final result:
The upshot is that I can pick Workflow in Sharing, then my Workflow, which I've saved to Safari.

Update:
confusingly it seems as if Shortcuts is only a rebranding of Workflow, so my instructions apply to it as well.
Last, you Firefox Focus has an open in Safari option.