Origins of "going" in "going to verb"

OED traces this "future intention" use to 1483:

51. Expressing a plan or intention that something will happen (usually soon), or making a prediction that something will happen, based on present events or circumstances.

    a. In the progressive with a following to-infinitive. To be planning or intending to do or be something; to be likely or due to do or be something.

    (a) intransitive. With auxiliary be (usually in a simple present or past form; rarely in compound or non-finite forms)

    1483 tr. Adam of Eynsham Reuelation xviii Thys onhappy sowle..was goyng to be broughte [L. agitur] into helle for the synne and onleful lustys of her body.
    2008 R. Rummel-Hudson Schuyler's Monster (2009) vii. 90 He found out his wife was going to have a baby.

It thus seems unlikely that English inherited this from Indian Pidgin.

OED give for the etymology

Cognate with Old Frisian gān, Old Dutch gān, gēn (Middle Dutch gaen, Dutch gaan), Old Saxon -gān (in fulgān to accomplish; Middle Low German gān), Old High German gān, gēn (Middle High German gān, gēn, German gehen), and Crimean Gothic geen (not attested in earlier Gothic), further etymology uncertain (see note).

The "note" is several pages long, although it does have a specific reference to sense 51:

With uses expressing the future (see sense 51) compare similar uses of the verb ‘to go’ followed by the infinitive in some Romance languages. In English, this is usually expressed with a progressive construction using the present participle (to be going to; compare gointer v., gonna v., gunna v., and gon v.); with a similar use of the uninflected form go in West African (especially Nigerian) English (see sense 51b) perhaps influenced by similar constructions in one or more West African languages.

51. b. intransitive. colloquial (chiefly Caribbean and West African). In the form go, with bare infinitive. To be planning to or intending to do something; (be) going to, ‘gonna’.

    1998 C. Okechukwu Predicament (2012) ix. 66 She heard a man boasting. ‘I go disorganize your dental formula.’

However, that use is merely transferring a construction from other languages into an English-like patois.