"Are you actually suggesting that a pulse detonation rocket could run continuously for years? Not a chance. It would shake apart from the concussions. No machine or living thing would survive an interstellar voyage. Nothing would work that long."

An Orion can take off from earth [and indication of how much thrust it can deliver], it offers "both great thrust and great specific impulse".
Therefore one could have something like 3 or 4 gees of acceleration. One would probably want to accelerated it near the Sun. So, you might have around 20,000 seconds [5.5 hours] of thrust at say 3 to 4 gee acceleration [29.4 m/s/s to 39.4 m/s/s] giving a velocity of [588 km/sec to 784 km/sec].
It would be inefficient and unlikely that one would operate it's thrust for weeks or months.
1 gee for 6 months is 154,526 km/sec [slightly more than 1/2 the speed of light]- at such speed the nearest star would take about 8 1/2 years

I don't think we will go to a different star within the next 50 years. And therefore other than an interesting puzzle I don't think it's practical to have any detailed plans of such a starship.

But I have posted about some ideas of how this might be done and these didn't include using pulse detonation. Though I do think that one could use pulse detonation. I don't think being shaken apart from concussions would be particularly difficult aspect.

If we looking at velocity of in the range of less than 1/100th the speed of light [less than 3000 km/sec] a significant portion of the velocity could have to do with Sol orbital speed [220 km/sec] and Sol's escape velocity [600 km/sec]. One also could consider using stages. And one should look for ways of how one could decelerate once one gets to one's destination [a task which could be more difficult than leaving Sol].

Probably what star one chooses goes to would an important aspect. You probably would want a more massive Star than Sol. A binary system, and/or a system with massive planets would also have advantages. Obviously if a black hole or neutron star was near us it could dominate any choice in terms of destinations.
So, before getting too excited one would need to know these sorts of things about where one was going.

Regarding Sol orbital speed around the Milky Way. We are apparently traveling at a higher velocity than we should be if the Milky way mass was comprised mostly of non-dark matter. We might want to know more specifically about that, before embarking on a interstellar trip. It might point to a way of getting more velocity.

As far as using pulse detonation, you want apply a lot of delta-v near the Sun for powered gravity assist.

So, with 588 km/sec to 784 km/sec of velocity added near the Sun you could have velocity of around 1200 km/sec- well above Sun's escape velocity. Per hour it's 4.3 million kph- or about 34 hours before it's at earth orbital distance.

In addition if one uses a solar sail which suppose gave average of .05 gee [.5 m/s] to Earth distance. So in 30 hours you added another 54 km/sec. So roughly one has 1250 km/sec at Earth orbital distance.
If you then assume an average of 1/50th [.02 m/s] of a gee, from Earth to say Jupiter. Jupiter distance is 778.6 million km from the sun, and require another 140 hours. And gains about 10 km/sec.
The distance from average orbital distance of Jupiter and Pluto is 5090 million kilometers, and at 1260 km/sec would take about 1122 hours [46.7 days]. Assume an average of say 1/100th of gee. Gaining about 40 km/sec.
So at Pluto distance it could traveling at about 1300 km/sec.
From 5870 million kms to the "edge" of our solar system:
"Oort Cloud.... estimated at about 50,000 AU (or 7.5x10^12 km)" so 7.5 million million km.
At 1300 km/sec requires about 1.6 million hours [182 years]. If one could get an average of an 1/1000th of a gee for next 10 years beyond Pluto orbital distance you could get additional 315 km/sec.