Ah great question about a local shop I actually don’t know of one - hoping someone else has an answer to this! I got my PFD online. Worth throwing an ISO on a local Buy Nothing group I wouldn’t be surprised if someone has an extra they don’t use.

Sweet, congrats! You do need to wear a PFD (personal flotation device) but this can be one of those ones that looks like a fanny pack and only inflates when you pull a string. Check out Fletchers Cove as well, there is much better (free) parking. I think Boating in DC charges a small fee for utilizing their dock there. I recommend going on the Potomac instead of the canal, and be extra cautious in shallow waters or where you see rocks (your fin will catch, unlike kayaks which fare better in the canal). Have fun!