Strava isn't planning to add any new sport types in the foreseeable future. But you can vote for the feature here just in case they change their mind:

well… 900 votes on Strava - I wrote that there are 30 million padel players. If Strava doesn’t follow the trend, like many others who doesn’t will be risky and other platforms becomes more interesting. Up to Strava as I do not believe in anything with those votes. 

Well it's the only official way. 🤷‍♀️ I can't imagine how ignoring the feature request process can actually help to implement a feature, but hey that's your choice.

There are tons of other sports that people ask to be added. The popularity of “padel” might be regional - I don't know a single person here to do that sport, never seen any events related to that, anything. Instead, there's a huge community around kickbikes/scooters (🛴) here in Europe, also missing on Strava. People keep requesting that but unfortunately, Strava keeps saying that new activity types aren't planned. When/if they reconsider, they might prioritize those with high number of votes.

Yes, I can imagine that strava devs are concentrated around the USA, in big cities which would limit the influence of certain sports that are big in other places that are more rural, or simply elsewhere.