The ETA portal lists USD 50 for countries outside South Asia and USD 20 for South Asian countries. It says the tourist ETA is free for 30 days for nationals of 40 listed countries from 25 May 2026, for Singapore and Seychelles (30 days) and the Maldives (90 days) under reciprocal and bilateral agreements, and for children of any nationality under 12 (up to 30 days).
Arriving from Nigeria, a yellow fever certificate is required: WHO lists Nigeria as a transmission risk.
Driving on a Nigeria license
Sri Lanka and Nigeria are both party to the 1949 Geneva Convention, so an International Driving Permit issued in Nigeria is one Sri Lanka is bound to recognize.
Whether a permit is required alongside your national license is set by national road law, which we have not checked for this pair.
International Health Regulations (2005), Article 36 and Annex 7; WHO International Travel and Health, Annex 1, 18 November 2022 (revised 3 January 2023)