turn signal flash really slow ...

It is possible obviously that it could be the signal switch itself since multiple light functions run through it.

The problem is that with aftermarket parts you could easily have worse or other problems unless you get OE parts.

Personally I would eliminate every other possibility first.
Ground the actual socket of every light involved.
Then if that didn’t do it I would replace the flasher unit with an electronic one.

THEN I would open the column and contact test it by connecting the corresponding points.
Basically jumping the contacts with a jumper wire.

Some people aren’t up to it, some are.
Some throw parts at it until it works, and that’s fine as well.
It’s just not how I do things.
I start with the simplest explanation first and work my way through until I find the problem.

Knowing that these cars are notorious for ground issues, that’s what I always verify without question first.