I really hope it'll work out, but we'll see.
I've heard binary distribution is a problem, with many overcomplicated methods like Appimage, Snap, and Flatpack. But it doesn't matter because linux users will prefer installing from source code or a trusted repository anyways. And they should: This is the more secure way of doing things. Closed source programs need not apply.
For me, 99% could easily be web-based, which makes "mobile web" the standard, and not necessarily "linux-phone."
Some can be operated via the web but they tend to require a hardware authentication token, which is as inconvenient as carrying a second phone (each bank requires a different token or card reader).
Some can be operated via the web but use their phone app as an authentication token for web access.
And some don't provide full functionality via the web at all.
Plus, the apps are way more convenient than logging in via the web in practice.
I opened a business account with an (at the time) exclusively mobile bank last year, because other banks took too long to authorize setup (they generally take weeks or even months), and I had a new company starting. I went with the only bank I knew where I could get set up within a few days to start taking revenue, as I had a client ready to pay from the start. It turns out that being mobile also meant they had a streamlined electronic setup process, and no visit to a branch during a pandemic. It still took a few days, as various people checked out my identity, read my LinkedIn profile to confirm what kind of business I was in, etc.
Last time I opened an account for a new company it took over a month and two in-person interviews, so the mobile bank was a big improvement.
Since then they have added web access as well, which is great, but use the phone as an authentication token, which is a bit annoying. It's not ideal, but neither are any other options I know about. Having to carry a separate physical token/reader around (or in practice, leave it at home and not have it when needed), as all the other business banks I've used require, is more annoying.
Not only is that unnecessary, it is also not practical as the entire purpose of Open Source is that if you do not like something you fork it and make it your own.
Linux on the Phone should absolutely avoid the Wall Garden draconian approach of iPhone and modern Android