Visiting shrines of Muslim saints is a common practice in India. These saints may or may not be Shia but there followers are mostly Sunni specially Barelvi Sunnis. Are we allowed to visit these shrines? The shrine at Ajmer and Dewa is an example.

Visitation of Muslims grave is recommended it reminds us death and hereafter one can prepare himself/ herself for aakherat
You can recite Fateha but don’t seek intersections of them to Allah for your wishes that you pray with the name of Prophets and Ahlul bait (as).
No doubt there were the few saints they were Shia and they conveyed the message of Ahlul bait as by hiding themselves as a Shia that was period of taqaiyah but there preaching was preaching and teaching of Ahlul bait as without naming them therefore most of the Dargahs managed by Sunni brothers.
Khawaja Ajmeri was Syed Shia and he was a scholar he was in the progeny of Imam Musa Al Kazim as
Khawaja Moinud din chishti s/o Syed Ghayasuddin s/o Syed Sirajuddin s/o Syed Abdullah s/o Syed Karim s/o Syed Abdul Rahman s/o syed Akbar s/o Syed Mohammad s/o Syed Ali s/o syed Jafar s/o Syed Baqar s/o
Syed Mohammad s/o Syed Ali s/o syed Ahmad s/o Syed Ibrahim S/o Imam Musa Kazim as
Nearly 950 years before he came
Shah Hast Husain was written by him and was Shia.
Syed Waris Ali Shah of Dewa Shareef was Sunni. May be was in Taqaiya was born in 1817 and died in 1905 his brother in law Khadim Ali shah is buried in Lucknow but his ancestors came from Neshapur Iran .
These are few known sufis but unfortunately in India thousand of Dargah but there is no history or authenticity.
My humble request better to visit Imambargah and pray for the ziyarat of Madina Karbala
Najaf and all other holy cites.