Hardware, gardening and home improvement supplies aren’t new niches for dropshipping. Because there’s already a decent amount of competition in these niches, it’s safe to assume that these niches are feasible.
If your supplier is located in the same country as your target market, having a return/exchange policy can be manageable. However, if your supplier is from overseas, the cost of shipping back the product to the supplier will become an issue to consider, since these are usually large and heavy products.
If you decide to ship from overseas, it’s safe not to offer returns/refunds at all because the shipping costs will be high. However, this would greatly affect your credibility and the buying confidence of your customers, especially that these usually are high-priced items.