When creating a device rule in snmpcollector probe templates, you can create a rule that chooses hosts based on a regular expression (regex).
The regex query should be placed inside the regex field without any beginning or ending constraints.
A typical regex query would look something like this: /.*/
This would resolve to select any block of text.
In snmpcollector device rules, you would enter the same query as:???? .*
In the above example you have removed the slashes.
You can easily test this by making a device rule with the same .* regex rule, it will then apply to all monitored devices where the template priority takes precedence.