Those 3 checkpoints do not allow to cross the border on foot.
Mamonovo/Gronowo and Nida/Morskoe have bus options.
Mamonovo – it’s better to take a bus in Elblag or Gdansk, could be too tricky to try and catch it near the border.
Morskoe – you can try to catch a bus there, but still – Zelenogradsk or Kaliningrad is a recommended starting point to avoid the risk of missing a bus.
There are on-foot options on other, less popular crossings.
I will be happy to assist you with that trip, need more details on your travel plan.
#stayhome now and
- Goldap is the on foot option for Poland
- Sovetsk and Kibartay – for Lithuania
or hitchhiking to cross the border at any point