@Con, Willkommen zu Forumosa.
Putting aside any COVID-19, I’m sure you’ll deal with that yourself.
So, where to go for surfing.
If you want to be near Taipei, then find a place in I-Lan County, about a 45-minute drive (depending on where you are) back to Taipei City.
There’s some big surfer community/beach near Toucheng.
The beach is Waiao Beach (can google map it).
However, that is like the most crowded one for surfers, as Taipei-ers drive over on the weekend for surfing there. There are various surfing rental shacks.
From there, you can go down further south, although in some of the links below, you’ll see other beaches to the north of Taipei and elsewhere in the north.
If you want the beaten-path route, go to Taitung County in the southeast.