Hey there,
Yes, WP-Forge supports all of the features found in Foundation, even interchange. Currently WP-Forge is at 5.5.3.1 and supports the 5.5.3 version of Interchange located here: https://foundation.zurb.com/sites/docs/v/5.5.3/components/interchange.html
I am currently working on updating WP-Forge to Foundation 6, which began yesterday and will take sometime to complete. I am all about WordPress standards and doing things the right way. WP-Forge is considered by many to be the best WordPress Foundation theme available and I intend on making sure WP-Forge 6 lives up to that expectation.
Keep in mind however that you do need to manually add the data-interchange attribute
to your content. It is not automagically done for you.
WP-Forge will support the 6.0 version of Interchange located here: https://foundation.zurb.com/sites/docs/interchange.html
WP-Starter is just a simple child theme, so whatever you want to do in WP-Forge you can do in WP-Starter.
I hope this helps and I hope you decide to use WP-Forge/WP-Starter for your project/s. Also, if you do decide to use WP-Forge please keep this thread in mind: https://www.ads-software.com/support/topic/support-issue-clarification?replies=1
If you need any further assistance or have any additional questions, please feel free to ask or post a new thread.
As always, enjoy!