Iranic/Indo-European p- = Turkish b-

[Vangşinas]

Tocharian B : Old Turkish
piś : beš, biš "five"

From Proto-Tocharian *p'äñś.

Middle Persian : Turkish
*pāčag : bacak "leg"

Reconstructed from New Persian pāča (in modern spelling "pāče") < pā- "ayak" + -ča(g) "diminutive suffix".

payrām : bayram "fest,"

"pay" like in Gorani "pey" (with, -ful) < *pad and Pashto "pə". So we see "pay-rām" (restful).

pābak : baba "father"

It is unlikely that is loaned directly loaned from New Persian, because in New Persian it were not expecting the form "bāb-ā" with Auslaut -ā, look to: bāb, bābak etc.

Khotanese : Turkish
pat- : batmak "fall, sink"

pat- in Khotanese has indeed the same meaning.

phaja : baca "oven"

From the verb pajs- "cook".

pīrna "first" : bir

From Indo-European *per- "before, in front, first".

Not sure:

PIE : Old Turkish
*pṓds : but "foot"

Zazaki/Kurmanji : Turkish
pırnıke/firnik : burun

Maybe from a special iranic source. "pırnıke" is the Zazaki one, "fırnık" is Kurmanji, the root at the both is:
pır(ı)n-. See also: Zazaki perraene : Kurmanci firrîn "to fly".