wala naman ibang way na makakabili ka ng Bitcoin direct na mismo sa e-wallets or banks.
This isn't an endorsement, but Maya has that feature.
You can buy BTC at ibang pang mga cryptocurrencies directly through their app, and the payment will come directly from your wallet's balance.

I'm pretty sure mayroon ding ganyang feature sa GCash since they have GCrypto. I just haven't tested that yet (mabagal kasi GCash app, I usually just use them for bill payments.

)
Banks, no idea. I rarely use their services nowadays.

Have not tried this ah parang bago lang sakin ang feature na ito, dati kasi from coinsph ako ppuntang poloniex ung 500 ko .1x na bitcoin na ata, buy bitcoin sa coinsph tapos send na sa poloniex, pero ayaw kung subukan iyan sa hirap ng support nila at saka baka mamaya if ganyan mangyare, or baka naman may bug lang with gcash, if meron naman maya, at stable naman baka duon nalang, hindi ko kasi sinusubukan madalas or pagdiko sure wag nalang ako gumamit, baka magp2p nalang ako.
sana maayos ni op issue nya sa gcash na yaan