For third party stylii, you'd be better off selecting smart bluetooth stylii from Adonit.
Adonit has many smsrt, bluetooth stylii that work with all base model 6th, 7th, 8th and 9th gen iPad models and have many more compatible, third party apps that work with them.
Wacom has NEVER had a good, active or smart, bluetooth stylii that work with Apple iPads, ever!
Here are Adonit smart, bluetooth stylii that will/should work with your 6th gen iPad model.
In descending order from highest price to lowest
https://www.adonit.net/noteplus/
https://www.adonit.net/note-m/
https://www.adonit.net/note2/
https://www.adonit.net/note/
https://www.adonit.net/note-uvc/
Many more third party apps support Adonit stylii than Wacom because, typically, Adonit stylii actually work with little issue with the more extensive list of compatible apps.
Most recent Adonit stylii offerings offer palm rejection, pressure sensitivity and tilt support for the base model 6th, 7th and 8th and 9th gen iPad models.
Here’s my “up to date”, comprehensive, but still incomplete, list of Adonit Note+ compatible apps for the base line iPad models, like the 6th, 7th and 8th gen and 9th gen iPad models.
MOST apps listed support palm rejection, pressure sensitivity and tilt, unless otherwise noted
Compatible Adonit stylii apps for drawing
Animation Desk
Amaziograph ( NO tilt support )
Art Studio Pro ( a direct Procreate competitor, just as good as Procreate )
Colored Pencil
Concepts
Forge ( drawing/sketching/concept/ideation brainstorming app ) ( NO tilt support )
Infinite Painter
Interactive SketchBook ( NO tilt support )
Jump Paint
Medibang Paint ( NO tilt support )
Procreate ( palm rejection, tilt support ONLY ) Procreate is STILL fully supporting Adonit smart, bluetooth stylii “unofficially” under the status of “unsupported stylus” message, but all Adonit stylii features and functions all still work as expected.
Tayasui Sketches/Sketches Pro ( palm rejection, Tilt support ONLY )
SketchClub
Vectornator ( palm rejection ONLY )
Zen Brush 2
Compatible Adonit stylus apps for Notes and Notes with drawing types of apps.
GoodNotes 5 ( palm rejection ONLY )
Note Shelf 2 ( NO tilt support )
Notes Writer ( palm rejection improved using special, non-electrical conducting, lycra-based material drawing glove )
QuickNotes X Pro ( palm rejection ONLY. No pressure sensing for light/dark or thin/thick lines )
uPad ( app self palm rejection, NO pressure sensing or tilt support )
Zoom Notes ( NO tilt support )
PDF Pen ( NO tilt support )
This is pretty much it for Adonit compatible note-taking apps.
This stylus works with other non-compatible apps, too, but without any palm rejection and/or pressure features.
You can use this stylus with other apps but will not be able to lay your palm on the screen, while you write or draw, unless you use special, non-body electrical conducting, lycra-based material drawing glove that works by isolating your hand/palm and allow you to lay your hand/palm on the screen as you draw in these non-compatible Adonit stylus apps.
Something like these found on Amazon.
https://www.amazon.com/AKX-Rejection-Drawing-Graphic-Sketching/dp/B08R6PWKC9/ref=sr_1_33_sspa?dchild=1&keywords=tablet+drawing+gloves&qid=1611535160&sr=8-33-spons&psc=1&spLa=ZW5jcnlwdGVkUXVhbGlmaWVyPUExMFg5WFBZWFpCS1kmZW5jcnlwdGVkSWQ9QTA5OTA2MzMxRUVYUURUMlAwVU4wJmVuY3J5cHRlZEFkSWQ9QTAxNDY1NjMxVjg1NE45TVRXSUQ3JndpZGdldE5hbWU9c3BfYXRmX25leHQmYWN0aW9uPWNsaWNrUmVkaXJlY3QmZG9Ob3RMb2dDbGljaz10cnVl
https://www.amazon.com/Timebetter-Rejection-Drawing-Sketching-Suitable/dp/B08DKGHYMS/ref=sr_1_21?dchild=1&keywords=drawing+gloves&qid=1611533128&sr=8-21
Many more makers of these types of gloves found on Amazon and in different hand sizes, as well!
Best of Luck to You!