Re. platform portability: i primarily write C code and have had very close to 0 issues regarding software portability (once one finally internalizes that unqualified "char" may be either signed or unsigned, depending on the platform, and codes accordingly, it's smooth sailing). On my home ARM servers i've had zero issues re. availability of tools which i'd expect to have on x86 systems. They "just work".
That is, i guess, to say: don't hesitate to try it out if you have the opportunity to do so.
[^1]: my current system is on loan to me from a generous colleague, so moving to an ARM hoster would be a new cost, which currently rules it out as an option. If i were paying full price for the current x86 box i'd have most definitely already looked for an ARM substitute.
Software might not be quite as optimized for Arm as it is for x86, but in practice you probably won’t notice. In fact, Arm might be faster because it doesn’t have hyper-threading so every vCPU is a full core.