What all tests would you recommend to someone before starting TRT in their late 20s? No doctors in my country prescribe TRT, so I'd have to manage everything by myself. I'm thinking of doing a complete blood panel (liver and kidney tests as well) and an echocardiogram, a calcium deposition score test and maybe a liver sonograph to make sure that the organs are anatomically fine and to get a good baseline before starting. Would be doing these and keeping a close eye on blood pressure, hematocrit etc while being on T.

All that follows is opinion and non advice:

First, make sure you have low T symptoms, if yes then go ahead and get a Total Testosterone test. Those tests may be a bit overkill, but if you have the resources then go for it.

If you have typical low values then you're probably primary or secondary hypogonadism. Starting with 140-160mg and seeing how you feel after 7-8 weeks is a good start. If you have higher values 500+ but have clear low T symptoms with no other reasonable causes after evaluated by a provider overall, then you're probably relative. You'd need a higher starting dose of 160-200mg, but remember it's best to start around 160mg then go up until you notice a side effect. There's really no reason to go above 200mg unmanaged since more side effects occur in that range. All of those tests you mention are good, but the vast majority of those issues are vastly more likely from someone at 200-300mg a week than lower therapeutic ranges.

Main opinion, don't go high at the start & listen to your body. Feel great? No issues? Stay at that dose. Feel like you have side effects? Adjust down, do some research, etc, but don't go up or just "live with them".