Customers should have the ability to separate unit types into subcategories with dropdowns in the customer booking portal.

For example:

On the unit type selection step, rather than have the full list of unit types displayed, you could have options for Small, Medium, and Large (or Ground Floor, Second Floor, Third Floor, etc). If you select Small, it will drop down to show each specific unit type in this category: 4x4, 5x5, 6x6, etc.

This would allow for more general groupings for the beginning of the customer journey. This would also be helpful for businesses that have a very large amount of different unit sizes, so it doesn't just display in one huge list to scroll through.