Ilford Ilfosol 3 is availabe in 500ml bottle, but I can't say anything about this developer. The previous version suffered from short life and it was never a successful product
Ilfosol 3 is a very good developer, economical at 1+14.
Regarding shelf life, there is no comparison between Ilfosol 3 and it's predecessor Ilfosol S
I normally decant the 500ml into 200ml bottles and during the pandemic, I can across a bottle I had labeled 18 months previous. It worked fine.
If the OP lives in the US, consider Claytons F76+, easy to dilute, 1 + 9, times for FP4, 5:30 at 20 degrees C or 5:00 at 75 degrees C; HP5, 7:00 at 20 degrees C, 6:00 at 24 degrees C. I you need to push then dilute 1 + 19 and process FP4 for 9:00 at 24 degrees C, HP5 at12:00 at 25 degrees C.
Lasts about three months in a partially filled bottle. in 1 liter concentrate; about $11.00 (US) from Freestyle Photo, Los Angeles, CA.
I will second Clayton F76+ (also rebranded as Arista Premium). Excellent results across different film types, liquid concentrates (1+9) for convenience, and shelf life is decent. The Arista Premium comes in both 1L and 2L bottles.