There's not a definitive answer... We hope to get a FAQ
Do you have any basis other than PF1 precedent for saying that these items don't function?
I think, until they clarify this rule, that everything with a constant effect applies. Everything. If you need to wield an item or manipulate it, or command word, or anything else to activate an item, then it won't work. For everything else that you just wear and forget about it because it is just always on, yes, it should work by the current playtest rules.
Given the tight math, if a caster shape-changes using dragon form, he "gains" an AC of 27, TAC of 24. That seems pretty much on par with an expected fighter's AC around 11th level. If that caster also has, say, +3 AC from bracers, that could mean he ends up with an AC that's 3 higher than the group's tank. Which would be weird and probably not intended, but does seem to be the rule as written.
Not being able to use a weapon is offset by "gaining" a decent attack modifier and lots of damage types that involve multiple dice so the shapechanging caster definitely doesn't need handwraps giving him attack bonuses or extra dice and since those are wielded, not constant, they wouldn't apply anyway. In other words, damage is fine without using any wielded magic weapons/handwraps.
If that caster also has, say, +3 AC from bracers, that could mean he ends up with an AC that's 3 higher than the group's tank.
Given that the caster could only do this maybe 3 times/day, it may well be within the design intent.
I think, until they clarify this rule, that everything with a constant effect applies. Everything. If you need to wield an item or manipulate it, or command word, or anything else to activate an item, then it won't work. For everything else that you just wear and forget about it because it is just always on, yes, it should work by the current playtest rules.
Given the tight math, if a caster shape-changes using dragon form, he "gains" an AC of 27, TAC of 24. That seems pretty much on par with an expected fighter's AC around 11th level. If that caster also has, say, +3 AC from bracers, that could mean he ends up with an AC that's 3 higher than the group's tank. Which would be weird and probably not intended, but does seem to be the rule as written.
Not being able to use a weapon is offset by "gaining" a decent attack modifier and lots of damage types that involve multiple dice so the shapechanging caster definitely doesn't need handwraps giving him attack bonuses or extra dice and since those are wielded, not constant, they wouldn't apply anyway. In other words, damage is fine without using any wielded magic weapons/handwraps.
Most of the level 12 characters I've seen in the playtest have 32 AC. Granted, most of those were in the Paizo stream of Heroes of Undarin, but the one I'm planning on using for the same part has 33 AC, 35 once her stance is up. That's a pretty far cry from 27.
Edit: I should note that handwraps won't do anything - the new attacks you gain from dragon form and other spells of that sort aren't unarmed attacks. They're their own type of attack that isn't natural or unarmed, and gains none of the bonuses.
Edit2: Looking at the numbers again, the dragon form numbers seem off. Elemental form 6th has AC 31/28, +19 attack, +13 damage. Dragon form has AC 27/24, +20 attack, +6 damage. Aerial form 6th has AC 31/28, +19 attack, +4 damage and double dice. I know dragon form has the breath weapon, but on pure numbers it's so far below the other examples that it's not really worth it.