So for these different exchanges, do they allow BTC to be transferred to a Ledger?
I bought some BTC using Mogo a while back, but they don't allow you to transfer your BTC to a different wallet.
I was trying to buy directly through Ledger but I don't think they have the option to buy using e-transfer (only bank transfer and debit/credit card I think)
Yes, the four that I listed all allow withdraws to external wallet addresses (your Ledger). I would do some more research into withdraw fees though, as they do vary a decent amount. Off of memory, Crypto.com charges 0.0004
BTC, Newton charges dynamic withdraw fees but will subsidize up to $5, Shakepay offers free withdraws, and I can't remember what NDAX charges. One of these options might be much more appealing depending on how much you plan on buying. I believe NDAX and Newton would have the best prices.