Can any modern GOP practices/policies/philosophy be traced back to Eisenhower?

[Okay, maybe Mike Johnson is a competent parliamentarian.]

Quite a bit can, even in the realm of domestic policy. The Eisenhower administration did have a basic amount of foresight and public-spiritedness that subsequent Republican administrations have pointedly lacked, but it was also the architect of the modern "nondenominational but explicitly theistic and implicitly Christian" expression of American civil religion (the "and I don't care what it is" remark, "In God We Trust" on the currency and "under God" in the Pledge of Allegiance, Eisenhower--raised Anabaptist--going out of his way to get baptized in a Mainline Protestant denomination in office, unprecedented levels of access for people like Billy Graham and Francis Spellman), of active homophobia in the American executive branch (Executive Order 10450, which was a deeply regrettable departure from Ike's more tolerant wartime stance towards gay people in the military), of performative preoccupation with budgetary discipline (purely on fiscal issues Nixon was arguably to his old boss's left!), and of course of this country's Killing Eve-tier passionate-yet-toxic love affair with car culture and suburban sprawl (I'm sure I don't need to explain the specifics on this of all secular blogs). Almost all of this was informed by Eisenhower's background in the Army, an environment in which conformism, censoriousness, bean-counting, and an obsession with large and terrifying cars are all genuinely assets and in fact necessary for the men under one's command to survive. I regard Eisenhower fairly highly as conservative Presidents go, but he was a conservative President in every sense of the word "conservative" that isn't deliberately prescriptive and tendentious.

[Okay, maybe Mike Johnson is a competent parliamentarian.]

of performative preoccupation with budgetary discipline

Maybe I'm not clear on what you're trying to say, but I disagree that the current Republican "performative preoccupation with budgetary discipline" can be traced back to Eisenhower. Federal debt as a percentage of GDP went down substantially during his presidency, and Eisenhower resisted tax cuts proposed by others in the party in favor of a balanced budget. Obviously Eisenhower was helped by a growing economy, but I can't imagine Reagan, Bush II, or Trump would have passed up the chance to pass a major tax cut (and in fact, Democrats cut taxes substantially after Eisenhower left office).

I'd argue that the current Republican approach to the budget can be traced to the Reagan Era, when Republicans began emphasizing tax cuts above all else, and when debt as a percentage of GDP almost doubled (from 1981 to 1993).

I was trying to express that Eisenhower had a genuine aversion to deficit spending that later Republican Presidents have performatively aped, and I wasn't really able to communicate that well succinctly.