In Arabic Allah is written as
اللہ i.e. there is no "u" sound in the end. In Gurmat at most places, this word is written as ਅਲਹੁ, ਅਲਹ i.e. the spellings are same as Arabic. At some places it is also written as ਅਲਾਹੁ, ਅਲਾਹ.
In Arabic, this word does not have an Alif (kanna) in the end but he (haaha) but mostly this word is pronounced as Allah and in Gurmukhi the spellings have been kept same as Arabic i.e. without Kanna in the end. The pronunciation of this word in Gurbani is Allah and not Allaho. The aunkad is there to denote that this is a noun in Ik-Vachan (singular).
Allah is not pronounced as Allah-hu in normal cases. Allah hu Akbar means Allah is Great. Hu is not part of Allah.
In the following Pankitis the word ਅਲਹੁ should be pronounced as Allah and not as Allaho, which is not same as
اللہ:
ਕਲਿ ਮਹਿ ਬੇਦੁ ਅਥਰਬਣੁ ਹੂਆ ਨਾਉ ਖੁਦਾਈ ਅਲਹੁ ਭਇਆ ॥
ਜਾ ਫਿਰਿ ਦੇਖਾ ਤਾ ਮੇਰਾ ਅਲਹੁ ਬੇਲੀ ॥3॥
ਅਲਹੁ ਨ ਵਿਸਰੈ ਦਿਲ ਜੀਅ ਪਰਾਨ ॥4॥10॥
ਅਲਹੁ ਏਕੁ ਮਸੀਤਿ ਬਸਤੁ ਹੈ ਅਵਰੁ ਮੁਲਖੁ ਕਿਸੁ ਕੇਰਾ ॥In the following Pankitis the aunkad of the ਅਲਹੁ has been removed because of the presence of ਕਾ, ਕੀ and ਸੇਤੀ etc but the Uchaaran is still Allah. In the Second Pankiti below the aunkad has been removed because there is Sambandhak ਨੇ Gupt after it:
ਕਬੀਰੁ ਪੂੰਗਰਾ ਰਾਮ ਅਲਹ ਕਾ ਸਭ ਗੁਰ ਪੀਰ ਹਮਾਰੇ ॥5॥
ਅਵਲਿ ਅਲਹ ਨੂਰੁ ਉਪਾਇਆ ਕੁਦਰਤਿ ਕੇ ਸਭ ਬੰਦੇ ॥
ਕਬੀਰ ਅਲਹ ਕੀ ਕਰਿ ਬੰਦਗੀ ਜਿਹ ਸਿਮਰਤ ਦੁਖੁ ਜਾਇ ॥
ਅਲਹ ਸੇਤੀ ਰਤਿਆ ਏਹੁ ਸਚਾਵਾਂ ਸਾਜੁ ॥108॥Bhul Chukk dee Maafi jee.
Daas,
Kulbir Singh