According to this report for the BWC RevCon, Namibia is considering NSG membership and is linking this effort to potential BWC accession:

On 25 April 2019, an initiative to universalize the BWC was launched by France via its embassy in Windhoek to encourage Namibia to join the BWC. France highlighted the importance of the BWC, the 2019 French Chairmanship, as well as the benefits of joining the Convention. France also expressed its intention to provide technical and judicial assistance for the accession process and the transposition of the law into national law in the event of accession. On 3 May, Namibia informed France that it was considering applying to the Nuclear Suppliers Group, and a prerequisite for joining the group would be for Namibia to accede to the BWC, alongside other treaties. For that reason, Namibia is reviewing the possibility of joining the Convention. Furthermore, Namibia was carefully considering the French offer of technical and legal assistance for the accession process.