I would support this but we need to be somewhat clear about why and when we want to push people to those sites.
Out of preference we want to keep people asking quality questions on our site so our first priority is getting them to reword their questions to be on topic here. Failing that then we want to push them to the other site.
For Hardware:
Questions seeking for hardware shopping recommendations are off-topic because they are often relevant only to the question author at the time the question was asked and tend to become obsolete quickly. Instead of asking what to buy, try asking how to find out what suits your needs.
For software:
Questions seeking product, service, or learning material recommendations are off-topic because they become outdated quickly and attract opinion-based answers. Instead, describe your situation and the specific problem you're trying to solve. Share your research. Here are a few suggestions on how to properly ask this type of question.
I would suggest we qualify this two statements of "how to ask" as "how to ask on Super User" and add something along the lines of:
If you are only wanting a hardware/software recommendation then you may wish to look at our sister sites [hardwarerecs.se / softwarerecs.se] but first consider reading their quality guidelines.
The problem here is that it makes the close reason very long and a wall of text which many people are not likely to properly read beyond "blah blah not welcome here blah blah".
Shortening the total wordage would be good, but keeping the overall meaning and intent of keeping users here is more optimum.