You could try to use the free version of SFOS and install Waydroid on it to use android apps.

(Waydroid is a community thing allowing to use android apps.
AlienDalvic is the Jolla paid system allowing to run android apps.)

[non tech]
About not paying a Linux system, I don't fully agree, as everyone must get paid for his work.

Linux is free.
Mushrooms are free.
If we go during weeks pick mushroom in the forest and go sell them to the market, won't we sell them for money? We must pay the car, taxes, fuel, and like others, all the bills at the end of the month.

I don't know Jolla enough to defend it but I know they worked a lot to make things possible. I had some other free phones with free OSes. I liked them very much too but I was sometimes not even able to make a phonecall.
I am pretty sure that we also paid for people who made maemo when we bought our new N900.

Remember that being able to work for free is a luxury. Asking others to work for free...
I'd love if we all could work for free. Sometimes we can, sometimes not. Developing money-free progs often brings other things back (reputation, work, ego...). Is it really free?

We have 4 XA2 in the family. 2 have paid version of SFOS. Mine runs a free SFOS. I tried Waydroid w/o success ATM and it already took hours. I don't imagine how many workinghours AlienDalvic nedded to be built but I can understand that people having a loan to pay ask money for that job.
[/non tech]

So, if you try Waydroid with success, as I didn't manage it ATM, please share...for free
Here is (one of the) threads:
https://forum.sailfishos.org/t/waydroid-on-sfos/7442