Is it okay to read the Gītā or Hanumān Cālīsā on my phone?
yes — the words are sacred in any form; just read with the same attention and respect you would give a printed book.
Scripture was first passed on orally, then written on palm leaves, then printed. A screen is simply the next medium. Reading the Gītā, the Hanumān Cālīsā or a stotra on a phone or e-reader, especially while travelling, is perfectly acceptable and keeps you connected to daily practice.
Keep a few courtesies that show respect: sit properly rather than reading in bed, avoid reading in the bathroom, turn off notifications so your attention is not split, and choose a reliable edition with the original verses and a faithful translation.
Many people still like to keep one printed copy in the home shrine for pūjā days and for children to see. Physical books carry family memories and handwritten notes. Use both freely; what matters is that you actually read, reflect and live by what you read.
Source: common practice; scripture moved from oral to written to print
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