Since Heavy-Duty Boots negates the effects of entry hazards lying on the holder's side of the field, I think that wearing Heavy-Duty Boots will allow the player to ignore the effects of standing on, standing in, walking on, or walking in some of the following blocks:
- Magma blocks
- Fire
- Soul fire
- Cactus
- Wither roses
- Sweet berry bushes
- Cobwebs
- Soul sand
- Campfires
- Soul campfires
Here are a few images showing the idea:
https://imgur.com/a/KrVM7nx
Maybe Pokemon holding the Heavy-Duty Boots will also gain these effects.