Have overpronation/bunion Podiatrist said custom orthotics not needed over counter good. Lace up shoes better for support than mary janes w thick strap?

All depend. All depend of the severity of the pronation and ethiology.Mild pronation can be treated with over the counter orthotics, however more severe pronation need custon made ones with especific characteristics incorporated into the design/construction to adrees the problem.
If your going. To put an orthotic in a shoe, than a lace up will give you more room than a mary jane.
Disagree. I find that a custom orthotic does much better in controlling over-pronation and taking some of the pressure off the bunion.