Yes it’s fine to use Elementor in a separate browser tab. And I recently added an option to make that workflow more convenient.
Go to Settings > Integrations > Sync Browser Tabs
With that option enabled, Microthemer will reload the site preview when you save changes in Elementor. And Microthemer’s styles will automatically refresh in the Elementor tab whenever you make a style change in MT (without reloading Elementor).
By the way, version 18.104.22.168 fixes a display issue when loading Elementor 3.10 inside Microthemer. Some one just reported it. I thought it worth mentioning in case that was part of the reason you wanted to use separate browser tabs.