Reddit reviews RMLeatherSupply - John James Saddlers Harness Needles (All Sizes) (Pack of 25) Blunt Tip for Leather Sewing … (Size 0 (1/0))

best needles for stitching.(get the smallest size)
https://www.amazon.com/dp/B07477V1LG/ref=sspa_dk_detail_1?psc=1&pd_rd_i=B07477V1LG&pd_rd_wg=inIc1&pd_rd_r=7GJ8QT1CT13GBZ10644S&pd_rd_w=5aMup

Thread i use (size 632 ecru)
https://www.rmleathersupply.com/products/copy-of-fil-au-chinois-lin-cable-waxed-linen-thread-size-632

Scratch awl - just get a cheap one, it does various tasks, but no need to buy a expensive one just yet

Pricking irons - budget? get Wuta 3.0 or 3.38
got money? KS Blades 2.7 or 3
blanchard not worth, they dont even come sharp

that stitching clam is fine, its the one i use, you have to tighten it up upon arrival

instead of a that mallet, get a poly maul, any cheap one will do, i prefer harder nylon heads because it hits harder than rubber tip ones (which have a bounce)

any cutting matt will do, but the thick green clear one is best (and retains my knife edges better)
https://www.rmleathersupply.com/products/japanese-thick-cutting-mat-370-x-270mm

creaser, get a wing divider (looks like a compass tool)

get a nice japanese skiving knife, its soooo useful for thinning edges, cutting thick leather, and various other tasks. problem is they'll eventually get dull (after a watch strap project probably) so get a couple stones for sharpening
I suggest a cerax 1000 and a rika 5000 when the time comes.

you may also want a hole punch iron (i personally have a osbourne one)

if you get a plastic template it makes your life way easier, getting straight lines and curves consistently is a challenge.

good luck!