When we have a custom content type with different filesets and fields, Volto offers a form similar to the one in Classic UI, i.e. using the center of the GUI.
When we add Blocks behaviour to our custom content type, then Volto shows the fieldsets and fields in the sidebar.
Is there a possibility to show the fieldsets and fields in the center of the GUI?
For complex dexterity types that want to use Blocks would be a better UX to be able to have the dexterity fields in the center of the GUI.
This is exactly the question we should consider. At the moment it seems to me that blocks are relegating everything not "compatible" with them. This is of course a legitimate option. But there is also the option to let both "co-exist" and let the user/developer decide which one should be prominent.
From the perspective of UX I personally would prefer a "co-existant" way. I don't like having relevant thins half hidden in a sidebar which is not the best place for editing e.g. richtext or similar fields.
This could be achieved putting the blocks editor in a (first) tab at the same level with the fieldsets tabs (and of course maximizing the tabs panel).
As I mentioned, the components are there. Now Volto places dexterity types on the center when no blocks enabled and re-places them in the sidebar when blocks enabled.
Why not (also) doing the other way round. Putting the blocks in the tabs panel when enabled. And of course, allow to maximize the tabs panel.