Interesting topic!
Quote Bitcoin white paper titled <Bitcoin: A Peer-to-Peer Electronic Cash System.> I believe that the essence of a "peer-to-peer system" is to operate without a central authority rather, the blockchain itself should facilitate transactions, regardless of the businesses involved or their associated fees.

In my view, the term "Electronic Cash System" signifies more than just transactions, it encompasses trades, cash swaps, transfers, and everything else we do with cash. While it may seem challenging for community to set up their own ATMs globally, businesses like Costco won't provide this service for free. They will need to incorporate not just the blockchain fees but also operational and maintenance costs, meaning revenue generation is a fundamental aspect of their decision.

Security Risk? yes, I believe they're significant. There's a misconception that Bitcoin users are all wealthy, base on my last check only about 1 million wallets holding 1 Bitcoin or more <Bitcoin blockchain> including those belonging to Satoshi ,exchanges, companies, and institutions. It's unlikely we’d see such entities withdrawing from a public ATM and sure not Satoshi which does bring up concerns about potential thefts. It’s puzzling why Bitcoin users are frequently targeted for crimes shouldn’t there be equal scrutiny towards fiat ATMs?

I support the notion that Bitcoin payment options should be available everywhere and that ATMs should indeed support Bitcoin withdrawals. However, this should be done through the blockchain itself + logical service fees, rather than prioritizing revenue for businesses. Before we can fully embrace such advancements, it’s crucial that the world gains a better understanding of Bitcoin, as BTC offers a groundbreaking solution to the issues in the broken traditional cash systems.

To clarify a few points:

- Just because you’ve used the same device for other crypto without issues doesn’t mean it’s safe as some malwares targets specific types of keys, backup files, .. etc.

- Testing with small amounts doesn’t guarantee safety as some hackers might target larger sums instead.

- Avoiding installing suspicious apps or files isn’t a foolproof way to ensure safety as there are many seemingly legitimate apps that can still compromise your data even screenshots and saved files thats include any data in your clipboard (I might share a topic related to this)

- Whether Coinbase is a good option or not isn’t the main focus here the OP topic is about moving his father's coins from a paper wallet to Coinbase since he is already a user of Coinbase I assume he is familiar with the exchange and wallet rules and knows how to use it <correct me if my assumption is wrong>

It’s important to note that not all hot wallets are compromised, not all devices are hacked, and not every online method is at risk <I use Blue and similar options on my iPhone almost daily for couple of years and I have never been compromised> However, there is a potential risk of exposure when using them without a solid understanding of security practices if you believe you have thoroughly evaluated your device security and you are confident that it's secure you can consider using the Blue wallet option but if you’re unsure about your device security it’s best to stick with the safer options suggested by LoyceV.

I completely agree with you on "there's always a risk" when dealing with funds in general regardless of the amount it's wise to consider the possibility of a compromised device and take extra precautions.

That said I didn’t want to veer off into a separate discussion about security since the OP was primarily asking about wallet options.
However, I did add a bold note to evaluate his device's security as it's an important aspect that can vary based on individual understanding and usage.

Thanks for bringing that up it's definitely something everyone should keep in mind while exploring wallets options.

I think when it comes to choosing between wallets it really boils down to personal preference and comfort level with the options available as each has its strengths and there's no one size fits all answer.

For instance, if you're leaning towards using your phone Blue wallet can be a great choice because it's user friendly and works on both iOS and Android devices.

Just remember a few tips to keep your coins safe:
- Always make sure to download any app from their official website to avoid any potential security issues.
For Blue wallet you can start here: https://bluewallet.io which will redirect you to the appropriate app store for your device.

- If security is your top priority I recommend looking into LoyceV's guidance on <Offline and running without hard drive storage> as this's one of the safest options available to minimize exposure to online threats.

- You may want to generate a new paper wallet from https://www.bitaddress.org for testing purposes this allows you to experiment with giving options using the test keys before proceeding with your actual key.

- Make sure to read up on the wallet you choose including details about the types of keys and formats it supports this will help you avoid any issues when importing or accessing your funds.

- Check reviews and community feedback on the wallet app you want to use this can give you additional insights into its reliability and performance.

- Before you transfer a large amount of Bitcoin it’s wise to conduct a small test transaction this way you can confirm everything works smoothly without risking your full balance.

Ultimately, it’s about finding an option that suits your needs best so take your time researching and evaluating what each wallet offers.

Feel free to ask if you have more questions