The GBA was released in 2001 and discontinued in 2010 in North America, and was considered on-topic as of 2016 (6 years post-discontinuance and 15 years post-release). The NDS was released in 2004 and discontinued in 2013. I believe it should be considered on-topic as of 2021 (8 years post-discontinuance and 17 years post-release). Of course, this only applies to the NDS, not the 3DS.
This question was inspired by a comment:
With the passage of time since the question was asked, I'd now disagree on the DS aspect: The DS line was discontinued in 2014, and the successor 3DS platform has now stopped production: nintendolife.com/news/2020/09/… . A look on Amazon UK only shows 3DS games for sale. On that evidence, I don't think there's any reason to object to the original DS platform being on-topic in 2021.
Note that I include the PSP in the question title because it was contemporary to the NDS.