"You retain the benefit of any features from your class, race, or other source and can use them if the new form is physically capable of doing so. However, you can’t use any of your special senses, such as darkvision, unless your new form also has that sense."
How restrictive is wild shape, really?
Would unarmored defense work while shape changed into a bear? A bear's skin is not as tough as a lizard's but somehow it has retained the physiology of a monk or barbarian when it comes to increasing AC?
If the Lizard Folk racial doesn't work while shapeshifted, I do not see how anything does. A panther is not normally resistant to poison like a dwarf, a giant snake doesn't have the biology to resist fire damage like a tiefling. An elven druid in bear form doesn't have the physical ability to be immune to magical sleep.
The intent could be the only racial abilities restricted are the ones that allow you to cast spells.
If a Lizard Folk magically transforms into a bear, it is not outside the realm of reason to think that bear's skin could be denser than the average bear, his fur more coarse and almost scale like. A Dragonborn druid might retain a lustrous red coat of fur that resists fire.
The only real answer to this is to ask your DM. I, as a DM, would rule that bears do not have lizardfolk scales and therefore do not benefit their natural armor.