Some people like to develop on a slower machine (do all their development work on the slow machine) so they catch things, others like to do all the work on the fastest machine they have, and only when nearing completion test things on the slower one. Both have arguments in favor - a decent compromise can be a "build on fast, deploy on slow" where it may be as simple as a shared folder between the two machines with Synergy or even Ventura's built-in equivalent for running the app.
Crippling a high Mac is still not going to effectively mimic a low end system. An end user device is a system of queues if you will think like that. The slowest/smallest/busiest link in the system determines the overall experience. Sounds like for your needs, you’re going to need a real low-end system that has real bottlenecks in CPU(speeds, caches, accelerators), mem(capacity and speeds), IO(capacity and speeds).
A throttled high-end machine will not behave like a low-end machine. Sure, they'll superficially both be slow, but not slow in the same way. There are differences in IOPS, cache sizes, and so forth you simply can't escape from.