Answer
Does MDPI give APC waivers for low-income countries?
MDPI grants waivers and discounts case by case rather than from a published country list. Applications must be submitted before the article is submitted and are assessed by the managing editor on two grounds together: the quality of the research article and the authors' ability to pay. MDPI states that more than 30% of its APCs are waived each year.
Detail
Why this is harder to plan around
With a country list, eligibility is knowable in advance. With a case-by-case assessment that also weighs article quality, it is not, and the deadline falls before submission rather than at it.