You cannot create a gmail without a phone number these days. There used to be work aroubda where you sign up for a gmail via youtube or on a smart TV (don't advise the smart TV one), but I'm sure that doesn't work anymore.
I think if you don't want the gmail associated with your phone number you just have to buy a prepaid phone. If you live in a country where you can't pay for prepaids with cash and without an I'D, then I don't know. Welcome to the ponopticon I guess.
I can't vouch for those paid SMS services, they seem like a scam to me.