preferably buy from someome irl - p2p, without kyc.. but if you're not in network of bitcoiners it depends on where u live

for canada I'd advice Bull Bitcoin exchange (kycfree, good privacy); for any other country w bitcoin atms or Azteco vouchers, go for that; otherwise buy w Robosats online

***withdraw onchain btc to bluewallet.io***

in worst case use Kraken exchange.. there you can withdraw over lightning = low fee, better privacy

***withdraw lightning to phoenix.acinq.co***

watch a btcsessions Phoenix and Bluewallet tutorial on youtube first.. it's easy (as easy as trustwallet) but good to understand the settings with these bitcoin only wallets