Most often the result is not fully accessible; browser and assistive technology is inconsistent; and implementations vary across the web. This is why it’s always better to use native selects with HTML/web. (Native components is also a better choice for native apps as well.) Don’t forget that HTML selects can be styled with CSS; see these resources by RTD, Filament Group, and LugoLabs.
If you must implement a custom select dropdown, you will most like need to use the ARIA listbox role, combobox role (which specifies a composite widget), and often a combination of those roles. The option role is also required and usually a few other ARIA attributes (for label, state, etc.).
Here are some great examples which will save many folks a lot of time!
On June 12, a Miami federal judge ruled that Winn-Dixie violated the Americans with Disabilities Act by failing to make its website accessible to blind and visually impaired users.
The lawsuit was filed by blind Florida resident Juan Carlos Gil who uses screen reader software to access websites. Winn-Dixie operates nearly 500 grocery stores in the southeast United States. Judge Robert Scola ruled that the Winn-Dixie website is a place of public accommodation because of its integration with its stores such as downloading coupons, ordering prescriptions, and finding store locations.
The court order states “the website must be accessible by individuals with disabilities who use computers, laptops, tablets, and smart phones,” and content from third party vendors must also be fully accessible.
The estimated cost of $250,000 to make the website accessible was not consider by the court as an undue burden and “pales in comparison to the $2 million Winn-Dixie spent in 2015 to open the website and the $7 million it spent in 2016 to remake the website for the Plenti program.”
This case is especially important because it’s an actual trial with a federal ruling, not a settlement, and thus sets a legal precedent.