I dunno, man.
Maybe you spoke regarding this Android tab in particular, but I got the feeling that your advice about getting a laptop is a kind of general in oppose to using mobile devices. If I got it wrong - feel free to correct me.
I actually started using this software on a device that’s considered quite dated - iPhone 7 and managed to complete several releases using it only (mostly taking it as a kind of challenge - putting myself into unfamiliar production/recording environment, etc.), not simplifying my workflow and limiting myself to any significant degree (through life I mostly used Logic Pro as my main DAW, for about 15 yrs) - it required a bit different approach in technical sense at times, but nothing impossible.
So if you’re stating that mobile systems can’t handle a live audio input and a USB midi controller at the same time, I would disagree 
saying it from my own experience. that’s for the case of recording stage.
as for post-production with all the insane routing that usually applies, 20-30 sidechain-involved-instanses of something - I admit - the device sometimes struggled (poor bastard), but eventually handled all of this with a bit of optimisation of the resource-usage from me along the way.
And guess what, I consciously decided not to go back to a desktop(/laptop)-based setup and continued to use a smartphone as a main machine, yet of course upgraded from the “7” to a newer device - SE-2020 in this case, since I decided to make this shift, which I can’t imagine being unable to handle anything in terms of sound-related-production etc. At least not yet and approximately in perspective of next 3-4 years.
I understand that my screen-size-preferences may not be for anyone - i’m a fan of 4.7inches and its portability and the one that always scales down the interface of anything on this screen to 50-70% and considers it a relaxing experience for his eyes loool. Still, if the SE option is not for everyone in these terms, there are plenty of those edge-to-edge-display solutions that deliver similar/identical CPU performance (XR, 11 at least) for those who struggle with smaller screens. And hell yeah, they can do full-scaled audio/music production without having to ever turn on a laptop.
So just to be clear, my point is not to argue but to help someone who actually has everything he needs in his hands to avoid the situation when he denies even trying to utilize the tools he has due to a common opinion that a truly “serious” setup can’t be something that excludes a desktop/laptop. The thing is that you need a device that delivers a certain performance capacity in a form factor of anything that will suit your specific eyes/hands comfortably enough for you to keep working on it - it may be a modern (but not necessary a top-tier one) smartphone or tablet as well as, surely, a laptop or a desktop.
P.S. I know that devices mentioned in my reply are from iOS world and the topic is about Android use case, just pointing out that all this nerdy boring text should be considered as a reply to the advice of getting a laptop, while it’s not necessarily better and most likely will not be the most cost-efficient option. A suitable mid-tier smartphone from 2-3 yrs ago, even from Apple, will have more affordable price, as well as maintenance/service costs - again, saying it from my own subjective, yet consistent experience.