Hello @mcopley and welcome to the community!
It’s great to hear that you are considering a migration to Frontity.
This is a great question, and it is also one of our obsessions, using Frontity shouldn’t impact the marketing / content teams. That being said, there’s still one feature that we have to release to make this 100% smooth: Post Previews. Good news are that this is a priority and it shouldn’t take long. If you are curious, take a look at this thread where @luisherranz shares his research: Does Frontity support Wordpress post preview?
Apart from the preview, you’ll have to review the plugins that your marketing team use, and see if they still make sense.
Regarding SEO, you are covered. We have released a WordPress plugin to add support for Yoas and All in One Seo Pack. You can take a look at the documentation here: https://docs.frontity.org/frontity-plugins/rest-api-head-tags
In addition I also invite you to take a look at this article, where we talk about SEO for Headless WordPress.
Regarding using any WordPress plugins with no restrictions, it really depends on each plugin. Some of them don’t make sense, others work out of the box and others need a bit of work.
If you already have experience building and deploying a Next JS application, then it should be easy for you to deploy Frontity in a similar infrastructure. Indeed, we recommend using now to deploy frontity: https://docs.frontity.org/deployment/deploy-on-now
You could develop a react fronted for WordPress from scratch, but there are many technical challenges to solve before getting it right. I invite you to take a look at our list of features, I guess that one of the most difficult ones is the SSR. Is also important to mention, that using Frontity you have a team 100% dedicated to maintain and keep improving the framework, so you can focus on your core business.
I invite you to take a look at our About us page, so you can have a better understanding of the origins of the project. I think it can help you understand all the value that it’s embedded in the framework.
Hope this helps! Feel free to reach out if you have more questions