Due to the nature of a WordPress Multisite install it is not even possible to have two different hosting packages for one Multisite.
A Multisite install is actually the same as a single WordPress install. The only difference is the configuration in the wp-config.php and in the options. The database used for all the Sites is also the same.
The different domains you use are all sent to the same Multisite installation.
Having two different hosting packages means also having (at least) two different storage spaces and databases, so you lose the advantage of Multisite in the first place.
Therefor the only things you have to watch out for when choosing a hosting package for a WordPress Multisite are:
- Handling of Domains (Possibility of having more than one Domain, creating Subdomains if needed and directing them to the right directory)
- Availability of Webspace (depending on your plans for your Multisite, you may need a lot of storage)
- General stuff concerning Webspace (availability, speed, …)