Your starting point is the “Use in North America” page. There is a wide selection there, some are easier to use than others.
The YHDC 100A/200A/400A Split core current transformer SCT023R is the easiest, and is a direct replacement for the “shop” c.t. Despite what others recommend, you should choose a current rating that is closest to but above the maximum current that you think you will ever need, plus a small margin for contingency. Although your service is rated at 200 A, it’s unlikely that you will ever demand that.
The next easiest is the Sentran - MODEL 4LSF. This requires a small modification to your EmonTx or emonPi: You need to add a second 22 Ω resistor in parallel with the existing burden resistor. (There are holes ready to accept a wire-ended component.)
The remainder are harder, and need you to remove the existing burden resistor to substitute a higher valued one.
A few words about sizing your c.t: US 200 Amp Service explained or Do I need a 200 Amp CT?
The answer to the alternate question is yes, it’s called an “interposing c.t.”, so you use a 5 A : 50 mA c.t. on the secondary of your 5 A c.t., feeding into the emonTx/emonPi. But of course, you have the errors of both to take into account. What is possible, but I don’t recommend it, is using an external burden on your 5 A c.t. to give you the required 1.1 V at 5 A - it will need to dissipate 5.5 W at peak load.