Pork pies and scotch eggs are widely-available savoury snacks in the UK, but jellied eels are not?

I want to make clear to the US folks here that there's about 2 or 3 cafes that still sell traditional eels, and it's explicitly a London food, not wider British cuisine. From the number of videos and articles I see about them though, you'd think the country was covered in Eel cafés. Honestly, covering them at all is tabloid ragebait content at this point.

Correct.

Pork pies even have a protected geographic designation now:

https://www.mmppa.co.uk/

Scotch eggs are a common, if old fashioned, pub snack and are sold in supermarkets.

Jellied eels are a London thing, mainly poor areas of central East London, and very very rare even there now.