Substance Sources To Get With Substance Painter?

As just an idle hobbyist, if I want to fool around with object creation and texturing in MSFS using Blender and Substance Painter, is the discounted perpetual license for Substance Painter 2021 on Steam likely to be as much as I’ll ever need? Or are Substance Sources a vital source of texturing materials for Substance Painter making it worthwhile to go for a $20/mo Indie subscription, at least to get a basic set of Substance Sources (get 30 downloads/mo with the subscription) and what might the Substance Sources be that form a basic toolkit for MSFS object creation? Has anyone compiled a list of “must-have” Substance Sources for MSFS for the different object categories in the sim? Or are there open-source versions of materials available for Substance Painter?

My inclination would be to buy the discounted perpetual Steam version ($119) and just subscribe occasionally for a month if there are actually handy Substance Sources to have.

Edit_Update: Opinions on how useful Substance Share is just to get started with texturing for MSFS or any other similar sites for free material textures?

Substance Share « The Free Exchange Platform » (substance3d.com)

Or with B2M3, can one basically roll one’s own texture any time from an image on the web? And is “stealing” a texture out of someone else’s picture copyright violation?!

Substance B2M3 on Steam (steampowered.com)

Further_Update: So I sprung for the discounted advance purchase of the Steam 2021 version of Substance Painter ($119) and considering what I’ve paid in the past on edX.org for MS courses, just the Substance Painter tutorials alone (73 total) make it worth the purchase- while waiting for the 2021 version to be released (01/26/21), one gets the 2020 version in the interim and the tutorials should lift many clouds of ignorance for me. Just spraying aluminum or concrete on the default object that loads with the START PAINTING menu choice is awesome!

Should say that the Substance Painter tutorials are essentially free on the web - but you can’t do them per se without Substance Painter - so essentially I am buying Substance Painter to do the tutorials.