I think that if we talk about mass adoption, it should mean that Bitcoin is largely recognized as a payment method. So I'm talking about the reality where you don't have to look for specific stores to use Bitcoin but can go to your regular ones and use Bitcoin to pay for groceries.
The number of stores accepting bitcoin is still just a handful but more and more merchants are gradually coming in. Besides Bitrefill is a good place to buy gift card to redeem and use the credit to buy things on Amazon if that is what you are looking for.
I know, scalability. It's indeed a serious problem. Is the Lightning Network the only solution? Is it even a realistic solution?
You should take a look at what LN is and how it operates. This will clear this doubt. It is the next step.
Now, I realize it won't solve all of the problems, because if there are too many transactions that are being put through like that, the number of unconfirmed transactions will be building up. However, I think it could be a solution for a less significant adoption step or as a temporary measure. What do you think about all that?
Well I think this is a problem of the debit card system. It is something that you have to accept if you want to use a debit card. Now the bitcoin payment does not work like it, money is sent instantly just waits for the miner to mine that block in which it gets included and the money is sent. Take a shorter time but both has its own pros and cons.