Unbelievable but yes we agree on something, LOL.

While I do use PS and LR for some such corrections, when I moved from Canon DSLRs to Sony Mirrorless in 2017 I did keep one Canon DSLR EF-mount lens, the Canon TS 17mm f4 Tilt-Shift Lens. I keep an MC-11 (EF-mount to E-mount) lens adapter on it, to use with my Sony bodies.

I prefer visualizing the correction directly in the EVF before I shoot. It is a superb lens, but was NOT cheap to buy. Even today it costs $2149 USD new at B&H, and still costs $1600 USD used. I long ago took the financial hit to buy this lens, so no need for me to get something else now.

There are some more affordable E-mount Tilt-Shift, Tilt, or Shift lenses available from Rokinon, Venus, TTArtisan
https://www.bhphotovideo.com/c/search?Ntt=E%20Mount%20Tilt%20Shift%20Lens&N=0&InitialSearch=yes&gad=1&gclid=CjwKCAjw-vmkBhBMEiwAlrMeF78YjiaASxn-yQRhJYaRG6l3YhMvX_JlQ4v7J8iw8_8a7gylcpbD8xoCpm0QAvD_BwE

Cheers and best to you.

For many years, I did architectural photography with a large format view camera- 4x5 or 8x10. I used leses that had a very large circle of coverage so that all the camera's movements, tilt, and shifts, could be employed without vignetting, fall of edge sharpness due to zonal aberrations, etc.

First of all, "architectural photography, in its "pure" form is not exactly the same as real-estate work or casual "snapshots" of buildings and other structures. A certain percentage of the work I do is commissioned by architects, who are very fussy about the accuracy, perspective, and particular view of the specific elevation of a building. There is somewhat of an overlap between architecture, real estate, and certain kinds of advertising assignments that have to do with buildings but all do not require the same treatment.

If the job requre the utmost accuracy, I have found that perspective control and any correction have to be addressed at teh camera. The view camer offered the maximum degreeof control become the front and back standards could be tilted, shifted and swung and a combination of corrections could be applied at the same time. A tilt/shift lens is the next best tool The most useful tilts, shift, and swings can be applied, but of course, the back of most digital cameras has no movements. A top-quality tilt/shift lens has a circle of cover that is necessary to accommodate its adjustment. If a photographer does a justifiable volume of architectural work, such a lens is a sound investment. If you know how to use it, it will deliver excellent IQ and save a lot of tedious post-processing procedures that may impair the final image quality.

I noted that someone wrote that the tilt control on a T/S lens is "useless" and can only be applied to close-up work The Scheimpflug principle can be applied to increase DOP in a font standard swing as well as a front standard tilt. This can be apple to increase DOP without excessive stopping-down thus, avoiding diffraction.

For the occasional job, there are many workarounds. A tall building can be accurately photographed without foreshortening or converging line distortion by elevating the camera halfway up the height of the structure. A nearby building, window, balcony, or rooftop can serve as a viewpoint. An elevating device such as a cherry picker or Sky-Jack can be rented.

Attaced, is an excerpt from an old Kodak Professiona Photoguide. It illustrates the most useful view-camera movements. Someof them are applicable to a modern tilt/shift lens.

As for the OP's question. I advise him to consider a T/S lens, that 17mm Canon is a beauty, AND assess your client's needs as to the accuracy specifications, and the size of the final exhibition of your images as the IQ requirements. There s no reason why you should not master the editing techniques that are used to correct perspective. Even if you acquire a T/S lens since the camer does not have a tilt/shift rear standard, you still might have to add some tweaking in post-processing.

Yes, there are conversions that make the adaptation of costly medium format lenses to current digital cameras. I have converted a Mamiya RZ67 to digital with a Phase I, a special tilt/shift bellows, and some view-camera glass. The conversion was very costly but I still use the system and it has paid for itself.

Those old Professional Photo Guides are great little resources. Of course, a lot of the film data and specifications are for materials that are no longer in manufacture and the ones that remain are mostly changed. The many calculator dials, charts, and illustrations about optics, perspective control, electronic flash data, and more are all still valid and applicable to digital technology.

I like to joke with the smart**s rookies and tell them that I have already forgotten what haven't learned yet but when I forget a formula or some technical fact, I pull out my little book- It's always in my camera bag, They are still available through used book stores and online sources.