Recommendation - Ring Pro Installers?

Any electrician should be able to install it. I'm sure it comes with instructions that should make sense to them and/or any competent CCTV installer or DIYer.

If they are only providing power and you set it up you should be fine in a domestic setup.

They can install any system themselves in a domestic setting and have an electrician commission the power since this is the bit that worries them.

Even most PSA registered installers are not RECI certified and in theory need to get electricians to commission any parts of a security system which need to be hardwired unless an isolation switch has been provided for them. I realize that the circuit in question is only low voltage and doesn't even warrant an electrician unless the transformer for some reason needs replacing.

Edit: Just to clarify, these are the ring install instructions https://support.help.ring.com/hc/en-gb/articles/360036047831-How-to-install-your-Ring-Video-Doorbell-Pro-with-a-hardwired-transformer . There is the possibility of needing to replace the transformer in the consumer unit, if this is the OP's concern with the install than any RECI electrician can sort out the circuit and the OP can simply connect the 2 wires to the ring doorbell. But not all PSA registered installers would be covered to touch the consumer unit.