I know Anon is a placeholder for anonymous, not the character's actual name, but in lieu of a name I'll be using it as one.
I really like the world-building and how it's subtly communicated through Anon's behavior and interactions with other characters, this game could easily have had a non-characterized protagonist that the player has full control of, instead the player shares decision making with Anon which I think does a better job of putting the player in Anon's shoes, because just as Anon is struggling with his mental health the player is struggling with Anon's personality. This co-pilot arrangement has the potential to be incredibly frustrating but from what I've seen so far it's handled very well, Anon does/says things that in his situation I would have handled differently but this isn't my story, it's his story, and it works because I can empathize with him. He doesn't just do stupid things because the plot demands it rather his behavior is very much in line with how that demographic thinks and behaves, and it's clearly a consequence of his circumstances and upbringing.
I know people like this, hell I am like this to some extent, I'm much better off than Anon but my mother also tried to OD herself, I used to live in share housing and even with the three of us paying our share we were struggling to pay rent and I remember having long conversations with my friends (granted it was mostly complaining) about how were we ever going to save up a deposit to buy our own homes?
Which segues neatly into my suggestions:
Perhaps Anon starts the game with some amount of student loan debt?
Mechanically this doesn't come into effect until the player has X amount of money in their account (i.e. they're making a decent amount of money) at which point the 0% interest student loan debt suddenly starts accruing interest (because bureaucratic bullshit) which actually puts the player in a position that's worse off than when they started. Now this isn't really a game that benefits from having difficulty that ramps up throughout the course of the game, the player wants to feel that they're making progress and that this progress benefits them, not that it's actively working against them (i.e. the Skyrim character level problem). But there's also the problem of making the game easy enough to be accessible to new players, but not so easy that once the player learns how to play they are suddenly able to curb-stomp every obstacle from that point on. So prior to the the player reaching the X amount threshold they're in a early game grace period, then once they reach that threshold the game starts proper and becomes properly difficult to challenge someone who actually knows what they're doing.
Perhaps Anon has flatmates?
Easy excuse to introduce more characters and story threads and these are characters that Jun can potentially interact with without her illegality being an issue, good flatmates have an incentive to keep each other around, especially if they can negotiate Jun being part of the arrangement which will of course comes out of Anon's wallet.
Perhaps Anon wants to save up a deposit and get a mortgage?
This gives the player a goal to work towards besides buying parts for Jun and it's another drain on Anon's finances, and if Anon's only choice is an apartment he not only has the mortgage and bills to pay but also rates and body corporate as well, so it actually works out to be more expensive than renting, excluding the fact that by paying a mortgage Anon is accruing equity and as the mortgage goes down so too does the amount of interest, assuming the interest rate is stable.
Possible Win Condition: Financial Independence
Once Anon owns his own place outright there's another threshold whereby if the player accumulates enough wealth it's assumed that Anon has enough money to setup a diversified share portfolio and live off the dividends with Jun for the rest of his life.