Can you open solutions for 1 student once that student submits the assignment?
There is not functionality in Canvas to directly address this, but you could create a no submission, no grade "assignment" that includes the solution as a file in the assignment description and use the Assign To feature to open it to individuals as they submit their assignment. For the file, you can use the Restricted Access option. This would only allow those you add in the Assign To area to see that specific assignment and access the file linked to it.
Another option would be to use Modules with Requirements set so that they must submit the previous assignment before going on in the module, with the next item being the answer key.
How Do I Add Requirements to a Module?
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