The possibility of Bayern Munich winning the Bundesliga trophy is very small so the Champions League will be more motivation for them to go further or even become champions.
If you look at the opportunities in the second leg, I think Bayern Munich has quite a big chance, they are only 1 goal behind Lazio and the second leg will be played at their home, of course the percentage for Bayern Munich to qualify is very large.
However, currently what is a bit of a concern is the performance of Bayern Munich's players which is quite poor with all the internal problems that this team is experiencing.
The bad performance would be from either the tactics of the coach, the abilities of the team working together or that of the Injured players who have been reported to be out and won't be part of the game they've played.
They're not looking good to be called winners of the Champions League, I don't think I'd agree with you on that part of your post. If they can maximize the chances and opportunities they have then, they will go a long way against Lazio.
The players are poor then the coach should have something to do, if he cannot control his dressing room then sooner or later he needs to leave despite agreements of leaving at the end of the season.
Players like Alphonso Davies and Joshua Kimmich all are being linked to leave the club at the end of the season.